It's hard to give an answer without knowing other variables - namely, what else is happening in your life. I can relate to this sentiment over the past few yea

It's hard to give an answer without knowing other variables - namely, what else is happening in your life. I can relate to this sentiment over the past few years. The other variables, for me, are that the demands of raising a young family have grown, my day job has shifted into more of a maintenance mode with less latitude for creative development, and my family has recently suffered a tragic loss. During this time, I've been astounded how much more difficult it has seemed to accomplish fairly straightforward tasks compared to just three years ago. So I've also wondered if my mental ability has been on the decline. Yet, this past year I've had two new interests spring up - one possibly a new career path, the other an avocation - and despite having precious little time to devote to them, I have been finding that I'm learning at a rate that I might never have achieved before - even in my 20s. I've somehow found myself with a "beginner mind" again, and at times I feel like I'm on fire. And I'm in my mid 40s. I can't explain where any of it came from (one path quite literally took off after reading a post on HN!) - it all seems spontaneous. My little piece of advice is to be aware of these kind of nagging thoughts that take hold in your mind. Ask yourself if they are provably true and, whether true or not, they could cause harm. You never know what's around the corner, so it may behoove you to stay open and keep these nagging thoughts out of the way!