Boy, Susan--we seem to be birds of a feather.
In agreement w/all your comments on motivation. Like you, I am also freelance (medical/health journalist, and ft student finishing up master's program)and need to be more motivated for same reasons. Also just turned 51 last month, and suffer w/same peri symptoms as yours. In fact, should be preparing to leave for my technical writing course as we speak, but exhaustion from a writing project in that course combined with another class requiring a 50-page research paper, and a Bowel Cleanse not going very well, just has me feeling slightly rebellious.
But it was helpful to read your post. Don't worry, somehow all this will work out...