You'll probably be fine. From what my parents say, you keep gaining effectiveness due to cunning, practice, and ability to see the obvious. At least until 65 or so, and not necessarily in all professions.

If you're particularly concerned for some reason, you might want to make a habit of giving to charity (not necessarily large amounts, but enough to form the habit). Using a contract to force yourself also sounds cool, but is probably just asking for trouble.