when it comes to getting fit, you dont really need anything fancy, like gym memberships, medicine balls, weights etc.
the most weight you should ever have to carry should be your own body wieght, so do press ups. the best excersice for upper body strength.
If you really wanna buy something to help u on ur way, get a pull up bar. you can get a decent one for about a tenner.
stick it in your door frame and do some pull ups, second best exercise for upper body strength (IMO) works for triceps and biceps.
sit ups are good for you aswell, but you need to combine them with running and other fat burning exercises, as sit ups tone the muscles in your stomach. If youve got a bit of extra padding their already, that stays and youtone the muscules underneath, making you appear fatter
the army has an exercise aptly named the "oh no", mainly cos when when you get given them, your reaction will be "aahhh f*ck"
to do them:
1) start in the pressup position,
2) do one pressup
3) then one squat thrust (from press up position bring knees up to chest, dont move hands off floor)
4) from that position jump up and do one star jump
5) return to press up position.
thats one rep ladies and gents. thats why its called the oh no.
also doing exerses in sets is the best way to do it, start at a number like 10, so do 10 pressups. have a 30second break, then do 8, break, 6, etc...
running is by far the best all round exercise though as it doesnt justhelp your legs, it works all round. and dont stop when yu get tired. stop when you feel like your about to die. if you stop when your tired and dont push yourself you'll never acheive anything.
hope this rambling helps
lol