hold one leg out in front of you, squat all the way on the other leg, keep balance, then stand up again, just using the muscle of that one leg. then switch legs and reppeat. Most people can't do this "pistol" exercise, even when hanging onto a pole!
another one, for gut, is to sit flat on the floor, knees straight, feet together. Lean back a bit, with fingers interlaced under navel, raise heels about 6" off of the floor, and hold that position. 1 minute is pretty good, 2 minutes is excellent, but I have at times worked up to 3 minutes, in my late 50's. I just did 2 minutes' worth and I don't average 5 minutes of ab work per week.
another one, for gut, is to sit flat on the floor, knees straight, feet together. Lean back a bit, with fingers interlaced under navel, raise heels about 6" off of the floor, and hold that position. 1 minute is pretty good, 2 minutes is excellent, but I have at times worked up to 3 minutes, in my late 50's. I just did 2 minutes' worth and I don't average 5 minutes of ab work per week.