Don't worry about your gray matter. I just turned 50. I'm lucky enough that my current gig is really enjoyable, and as a result I am programming better now than I ever have. As others have said, follow your passion. I've drifted back and forth between tech and management several times in my 30 year career, and its clear to me that I am happier, and therefore more productive, when I am purely tech. But to each his own, you might be happiest in management. And finally, don't think your decision now is permanent. You can probably change roles two or three times in your 40s -- I did.