here's some tips...
1) EAT RIGHT!!! A couple years ago I was a little chunky so I started comin home and havin an apple or orange or some other piece of fruit/vegetable and a big glass of water...lost a lot of weight and developed decent muscles for not doing much...
2) WALK/RUN- start up a running or walking routine...if you have trouble running, start with a fast walk for 1/2 an hour (or more, if you can) or so, then eventually start running...the more you run/jog instead of walk, the quicker you'll lose weight. When you first start running, I would say aim for around 2 - 10 to 12 minute miles, then work from there...if you walk, try to walk every day or 6 days a week...if you're running, try to run 5 days a week - but if you feel overly tired, sore, or cramped, don't run as hard...maybe just go out and run a couple sprints or do jumping jacks instead - something that would use the sore muscles less but still get your heart pumping and in turn, burn fat.
3) IF YOU START TO CRAMP WHILE RUNNING:
Make sure you stretch a lot before doing any exercise - stretch every muscle you can think of and then some...but if you do cramp, try these quick fixes so you can keep working out, and remember to stretch more next time!
If your chest/stomch/side cramps up, do trunk twists - twist
your upper body to the left and right to stretch your torso.
If your arms/shoulders cramp up, do tricep stretches - put one arm over your shoulder like you're scratching your back, use your other hand to gently push your elbow back...you should feel a stretch in your tricep. Also, another good stretch is - bring your arms to your sides, bend your elbows to a 90 degree angle so your hands are sticking straight out in front of you, and bring your elbows back behind you - you should feel a stretch in your shoulders and upper back, as well as in your triceps and elbow tendons.
If your legs cramp up, do any of several leg stretches
Toe touches (both with your feet together and with them crossed (left foot over right foot, touch your toes, then right foot over left foot, touch your toes)
Quads - while standing, bend one leg up behind you and grab it with your hand. Pull your foot up behind your back, and you should feel a stretch in the front of your leg...keep your back straight while doing these.
These should help with cramps you get...other stretches before *and* after can only help - remember to stretch as much after as before running, it will help greatly with soreness and in the long run build and tone muscles faster with less risk of tearing or pulling muscles.
4) BE DISCIPLINED - SET A GOAL AND STICK TO IT!!!!
If you run for 20 minutes and decide to run for an extra 5 or 10 the next day, STICK TO IT!! You will feel more tired and quite possibly want to stop, and you might be telling yourself that it was too much, and that you'll just go back to 20 minutes the next time. **DON'T LISTEN TO YOURSELF!!!** Keep going, push yourself for those extra 5 minutes - when you finish them, you'll feel great knowing that you pushed yourself the extra mile (no pun intended).
Also, the more you run, the more endorphine(?) your body releases - endorphine is the chemical in your body responsible for creating what is referred to as "runner's high" - if you run for a while and get your heart rate up for a decent amount of time, when you stop, your body will feel lighter, and it will feel easier to walk - it's pretty cool...
5) DO OTHER EXERCISES TO BUILD MUSCLE
Do exercises like the ones found here:
Stretches, Work Outs, Routines
There's a lot of great exercises there that don't require extra equipment to do - pushups and situps, although basic, are not overrated - they're great for developing your upper body. I personally like diamond pushups because they work your triceps - after doing them, when you straighten your arm out, you will see a noticeable bump running along the back/underside of your arm - that's your tricep bulging - chicks dig it

and it makes you look strong even if you're not
6) GOING TO THE GYM IS GREAT, BUT IT'S NOT REQUIRED
A great major muscle workout routine using only dumbbells (free weights - you use them with 1 hand) is this:
Week 1 - Every day unless noted:
10 regular pushups
10 diamond pushups
30 situps
30 crunches
10 curls for reps each arm*
1RM curl each arm**
10 shrugs***
30 wrist curls each wrist****
50 squeezies each arm*****
1/2 hour walk (6-7 times a week) or 20 min. jog (4-5 times a week)
Each week add:
5 regular pushups
5 diamond pushups
20 situps
10 crunches
10 curls for reps each arm
1RM curl each arm
5 shrugs
15 wrist curls
30 squeezies each arm
10 mins. walk or 5 mins. jog/run
Good goals - after 6-8 weeks:
50 regular pushups
50 diamond pushups
150 situps
100 crunches
100 curls for reps each arm
1RM curl each arm
50 shrugs
150 wrist curls
250 squeezies each arm
3 x 7 minute miles
You might look at the goals and think they're impossible, but you'd be surprised how easy these exercises become after doing them every day for 2 months - stick with it and be determined - you can do it!
Notes on exercises:
* = CURLS FOR REPS - sit down and rest your right elbow on your right knee. Using a free weight (dumbbell) of 10 -15 lbs, slowly lift to your shoulder and lower the weight back down until your arm is straight. Repeat with your left arm on your left knee. You can use the arm that's not lifting to hold your elbow in place so it doesn't move all over your knee. Try not to use your back to build momentum to help you lift the weight - it can cause back pain and actually does less to your arms.
Any exercise for repetitions (# of times) tones muscle - it makes what muscle you already have look bigger and, essentially, better, but actually strengthens you slower.
** = 1RM CURLS - 1RM stands for 1 Rep Max - it means that you lift a lot of weight, so that you can only lift it once before you get tired. Think of it as the maximum amount of weight you can lift one time. Use the same process as above, except use around 25-30 lbs (just a guess - you will have to find what weight is good for your own 1RM). Notice that over the entire time, the # of reps stays the same - 1...after 6 weeks or so, you're still doing 1 rep, just with more weight. You'll have to judge for yourself how much weight to add each week, or, depending on your weights, you might have to add 5 lbs every 2 weeks (or something like that - use your own judgement).
Exercising for 1RM builds muscle faster than using less weight several times, but doesn't make the muscle as "obvious" or big-looking as several reps with less weight do - It's important to use a combination of reps and 1RM when lifting to strengthen and build muscle, and tone it to look good for the ladies and/or guys
*** = SHRUGS - while standing up, pick up a 10-15 lb free weight in each arm. Keeping your arms straight, shrug your shoulders so that the weights raise. Another way to achieve a similar effect, although it's harder, is to stand with the weights in each arm, and, keeping the weights close to your sides, lift them up as high as you can - your elbows should stick out and the weights should remain as close to your sides as possible.
**** = WRIST CURLS - sitting down, grab a 2-5 lb. weight in each hand. Curl your wrist towards your forearm like you were trying to touch your wrist. Uncurl your wrist so that your hand forms roughly a 90 degree angle with your forearm. You might have to do these one wrist at a time to make sure you're not cheating...
***** = SQUEEZIES - You'll need a little piece of equipment for this one - I attached a picture of what they look like - they cost under $5, and all you do is squeeze them -
here's an example of what they look like - it's the red springy looking thing about 1/3 of the way down the page selling for a whopping $3.50.
What do these exercises work?
Regular pushups - some biceps, mostly pectorals (upper chest near your nipples - you know, Arnold Shwarzennegger "boobs"

.
Diamond pushups - triceps (back/underside of your arms)
Situps & Crunches - abs
Curls for reps - tones biceps, some forearm
1RM Curl - strengthens biceps, some forearm
Shrugs - Peaks - muscles going from top of shoulders to neck - if you strengthen them they slant up from your shoulders to your neck.
Wrist curls - forearms, wrists
Squeezies - forearms, "golf balls" - muscle on outside of arm next to elbow
Walk/run - legs, endurance, burn fat, cardiovascular health
The entire routine, not counting time to run/walk, takes around 15 minutes at first, and builds up to around an hour or so by the end.
I'm not a professional trainer or whatever (so I'm not responsible if you somehow find a way to drop a weight on your face and die

) but these exercises work very good as something you can do in your room at night or whatever - have fun with it, find a way to make a game out of it or turn it into something you don't mind doing - listen to pump up songs - songs that get you excited and that have a beat - they'll pass the time much faster and get you excited and you'll be done before you know it...Good luck - and remember: STICK TO IT!!!