I have an idea for you, FF. For those days when your gym is closed, do gigantic sets of pushups. Don't count; do 'em 'till you up and need a tissue because you are CRYIN'. The last time our gym closed it was for some stupid plumbing issue or something, and I tried that. I think I did three sets. Man, my chest hurt for a week.
...And yes, I did need a tissue myself.