Another good workout is to do one push-up, then roll over and do one sit-up. Roll back over but this time do 2 push-ups and then 2 sit-ups. Keep increasing the number by 1 each time. Whenever I run the class at my karate school, I usually take them up to 20. It really helps to build up endurance. The easier version is to start with the high number and work your way down. It's easier because as you get tired, you have less to do. I prefer to go up though. Its easier to set goals that way.
Bob
Bob