New best story on Hacker News: Ask HN: I'm 40 and feel my mental ability declining. Programming seems harder.

Ask HN: I'm 40 and feel my mental ability declining. Programming seems harder.
453 by Buttons840 | 413 comments on Hacker News.
I'm around 40 and recently I have been asked to port an API from one language to another. The code I'm porting is average code, not terrible, but plenty of little things to complain about. I feel like my past self could have handled this task, but I am really struggling. Porting this API will require a deep understanding of the existing API, which, of course, has several layers of abstraction. I can't seem to hold more than about 2 levels of call stack in my head. There's the entry point function which calls other functions, which call other functions, which call other functions, etc. You know how it is, code calls other code, and logically it forms a tree of calls and return values that often goes several layers deep. I struggle to hold more than about 2 levels of this call stack in my head. By the time I'm down in the weeds I've forgotten what I'm doing, what the purpose of the actual API call is. I don't know how to break this into small enough chunks that I can understand it or make progress on. Imagine I gave you the code for the sha512 algorithm, and a hash, and asked you to find the pre-image (the input). This is how I feel. Where do I even get started? How do I find even a single chunk of manageable work to break off. The hard part is, several other developers are making progress on porting this API. Why can't I? What happened? I don't know if this task is just an especially bad fit for me, or if my mental abilities are declining?