I think that climbing the ladder to your roof 20x/day would be great for your leg muscles! I have managed (with God's help, I believe) to establish more discipline in my life over the last year regarding exercise. I do get at least 45 minutes 5-6x/week. I have finally gotten to the point that I miss it when I miss a day or two. That is good motivation for me.
Congratulations. You make the time for exercise. That's what I must do too.