o my god !!!
i hate to tell you this but you're wasting your time
it is scientifically proven that doing an amount more than 15 repetitions per set will not make your muscles any bigger, the only thing u are doing is increasing your local muscular endurance ie. you are NOT going to get bigger muscles
The fact that you are trying to get in shape is great but the cold hard truth is that u will NOT get big muscles simply by doing situps and pushups.
Buy yourself a bench (or make one, its not that hard if u have have a welder and some cheap square metal tubing)
Buy some weight plates 1.5kg, 2.5kg and 5kg to start with...two fives and 4 of each of the others.
Get a bar and two dumbells and you're set!
If this is too expensive then PLEASE do not bother doing what u are doing now! Be creative. find stuff around the place that is heavy enough that u can only lift 10-15 times at first!
Me and a friend began benchpressing (on the floor) bags of wheat!....and when they went we had to resort to fertilizer !.....thats when we made a point to find the money to buy proper equipment !
Get back to me if you want more detail on anything.
your friend muscle man sam!