Can't Lives on Won't Street

Every time you say you can't, it really means you won't because if you're able-bodied you can actually do most things you set your mind to, especially in America.  Saying you won't, though, puts the responsibility in your court and is often met with nagging, pleas, and other things that are hard to deal with without a tumbler of gin.

Stick with can't and bring up inarguable truths like genetics and parole requirements.