That which is usually called dotage is not the weak point of all old men, but only of such as are distinguished by their levity.

Ageing is not one thing that happens to everyone the same way. A mind that was serious and worked hard often stays sharp for long, while habits of carelessness formed early tend to show up enlarged later on. This is not a claim that decline is deserved, since much of it is illness and luck. It is that a good deal of what gets blamed on years was already there at forty.

Look at the habit of attention you are building now, because you are building one either way. Reading, remembering names, finishing what you start. Those are deposits on a version of yourself you will meet much later.