(GSR makes fun of me for counting half-pounds, but I say take the encouragement anywhere you can get it! ;-)
I've decided to totally re-vamp my push-up plan. Ultimately, I don't want to make the investment to do 100 push-ups in a row. So my new goal is 100 push-ups in 5 sets (of 20, math wizards ;-) with 2-minute rests.
Here's another change I've made: I really felt like I wasn't recovering with only one day of rest between workouts. I remembered that back when I was lifting seriously we rested two days between workouts of major muscle groups (chest and arms, back, legs). Plus, I was sore all the time. And it gets harder to build muscle as we get older (if you're not on supplements).
So, I made the change and am much happier. I'm not sore all the time and I'm able to add about 2 push-ups per workout. I've stopped using the 100 push-up challenge weekly sets and am just adding 2 push-ups per workout.
I did 80 pushups last night in 5 sets with 2 minute rests. Not bad. Again, obvious math: if I'm able to proceed without a hitch (bi IF!), I'll reach my goal in 5 weeks. My plan then, for those of you who care, is to take a week off and then go back to dumbbell exercises for my arms, shoulders and back. Maybe I'll alternate some with push-ups. I don't want to lose my hard-gained ability! Something else I'm thinking about long-term is improving the quality of my push-ups. I think they're all legit right now, but they could be a little better. I'm sure they don't meet the CrossFit standard ;-)
For something even more hardcore, check out this CrossFit Journal pdf. This is for the Walter Stokeses of the world (Walter is a beast and belongs to CrossFit in Austin). I'm really only looking for 80th percentile fitness (which Pareto says is achieved with 20% of the work it would take to get to 100% ability). My ideal would be to do 30 minutes of moderately strenuous exercise 6 days a week (except when training for RAGBRAI ;-).