I'm in my early 30s, have been programming for 10+ years and have this from time to time but as another comment said I don't think it's age related but more bur

I'm in my early 30s, have been programming for 10+ years and have this from time to time but as another comment said I don't think it's age related but more burnout or general tedium of the task. As I get older I do notice I have to force my brain a bit more to do boring tasks like the one you're describing, it feels like I'm not necessarily mentally declining but have less patience for these kinds of tasks and have a better idea of what I'd rather be spending my time on (creative tasks, friends, family). Also anecdata but I'm finishing up a project in which the CTO of the company has a good 15 years on you and seems as sharp as ever.