Sit-ups and Push-ups

[Clint]

Some do but honestly not all that much, so I don't really factor it into my exercise choices. Especially since a push up isn't really all that different from a bench press.

That being said I really like one handed medicine ball pushups where you do pushups with one hand on the floor and the other on a medicine ball held all the way out from your body so you can only really use it for balance.

[strife]

If I were you I wouldn't just focus on sit-ups and push-ups unless you only want an upper body physique to impress people at the beach. When I was training I would do Frank Shamrocks "100's workout" 2 times a week.

100 squats, 100 sit-ups, 100 push-ups, 100 shots, 100 srawls, 100 bridges, 100 elevators, and 100 stand-ups. Taking a 20-second break in-between each exercise before moving onto the next.

Since you seem like you just want it for personal gains and not so much training I'd cut out the shots, sprawls, elevators and stand-ups. Change the 100 squats to 100 jump squats and you have a pretty good core exercise to do at least 3 times a week. Try it out and add the other exercises if you want. This should help build muscle endurance and work your cardio as well.

[Monsterman]

You can gain streght with doing only push ups. Easy way to increase resistance is to put a box under your your feet, the bigger the box the bigger percent of your bodyweight is on your arms. When you feel strong and comfortable doing push up with the box under your feet, you can take the next step and put smaller boxes under your hands. That makes the movement longer and much harder to do.
This was just an exercise you can do instead of bench press, with my english it would take a week to tell you about training the whole body. But you can become stronger without going to gym, by doing one legged squats, pull ups, push ups, sit ups etc. With little changes you can make the movements either hard or easy, depending how many reps you want to do.
And don´t worry about the numbers, do as many reps as you can do with good technique, and don´t do sets to the absolute end.

[Metalhead]

Do as many as you can whether it's 5 or 500 then do ten more.

[WMP]

I do push ups on my fists, on my fingertips and I do Hindu Pushups. I also do pushups with my feet elevated on my bed and my hands on the floor.

I do sit ups without any momentum. I leave my hands by my side and just sit up and got back down.

I also do this exercise...it's me in the pic...