Crumbs, not at 50! Give it another 20 years!
Is there something you've always wanted to do or try, to give you a new interest and perhaps a sense of achievement?
I know more than one person who started playing the piano as complete beginners in later life or after retirement, and have thoroughly enjoyed it.
I turned 70 not long ago and did feel that milestone somewhat, but do try not to dwell on it. (And preferably look in the mirror without my glasses on so I don't see every wrinkle, though this does carry the danger of not seeing the odd chin hair, so can't stick to it all the time.)
It was in my 50s that I finally found success with something I'd been working hard at for quite a while, and did an OU degree too.
Just as well I did both then - later years were very much taken up with elderly parents/in laws, and now grandchildren. I just wish my energy levels were as good as when I was 50.