I have found overwork has caused the symptoms you describe, but not so much getting older. As a developer in their early 50s, I have certainly noticed becoming

I have found overwork has caused the symptoms you describe, but not so much getting older. As a developer in their early 50s, I have certainly noticed becoming slightly slower, but in no way less creative. I have seen colleagues work effectively well into their 60s, but I suspect this is different between people.