I have had many times feeling as you describe...
Right now, I am 61yo and on an upswing----feeling good, getting out and about, I think working at summer camp (I am an RN) is really helpful, as is doing school nursing when I can----(& being grandma helps too)----kids really don't care about your age when it comes down to it, as long as you are interested in them---and the energy is contagious.....I walk, I sprint, I ride a bicycle and jump in the lake to swim---it feels damn good. (...hard to imagine those days of going to work, to come home and nesting in the corner of the couch...talking myself out of doing anything...nothing mattering...-----though I know it could happen again...)
Hang in there, try to push something, dancing to music that makes you happy, in private if need be...climb a tree...silly things sometimes are the best...