There's a program called 100 Pushups -- the idea is that "anyone" can build up to doing 100 consecutive pushups after completing a six-week training program. Three days a week, you do five sets of increasing difficulty, for example 14, 19, 14, 14, 25.
Unfortunately, the program doesn't really account for the fact that muscles don't build as quickly as you get older. Nor does it warn you that it starts out pretty fun, but gets excruciating as you head into week 4 or 5.
This is not me :)
No matter - if you don't complete a day, you just repeat it until you do. Truthfully, I've been working on the program for over a year, but every time I build up into week 4, it gets to be such an exertion that I wimp out and skip doing pushups entirely.
Finally realized that it's more important to stay in shape than it is to complete the program. So I've gone into "maintenance" mode, doing Week 4 Day 2 over and over again. It's just strenuous enough to be a good workout, but not so intense that I skip them.
Still, I'd like to pick up the pace again sometime and complete the program. It would feel amazing to do 100 without stopping.