I've been a decent mid-level dev professionally for a long time now but been in a sort of rut for about as long as I can remember. Outside of work (which is going fine), I just don't have anything programming related to do. I keep myself busy playing with new tools and languages when I can be bothered but if I really think about it, I just don't have
any problems to solve with these tools.
I could lock myself in an empty room for days and come up with nothing. I've been waiting for an "idea" to hit me for nearly 10 years, I don't use any open source software that I could contribute to at all, and I lack the creativity to come up with "just for fun" projects. I feel very stagnant and I just don't know how to move forward anymore. Am I just hard-wired to be mediocre?
Have you considered the possibility that you're actually clinically depressed? Working on the assumption you are male, I think a lot of guys don't realise that low-grade depression looks like this for a lot of us. Especially getting towards mid-life.
One thing I would suggest is to embrace boredom. Cover up your television, delete your streaming video apps, cut back on social media as much as is possible, stop gaming if you game. Stop avoiding boredom with low-energy solutions.
Get really, really bored. Then see what your brain wants you to do. Boredom is a precursor to a creative state.
Another thought: consider if your "worthwhile" is actually helping other people do theirs? If you can learn new tools and languages easily, could you help others? Could you teach?
I need this change in my life too, and this is the direction I hope my life is heading in.