I learned to nap badly before I learned to nap well.

The first six months I tried to nap, I broke my night sleep — I'd doze for an hour at four, wake confused at five, and then be wide awake at midnight. I almost gave up. What worked the second year: a fixed window (1:00–1:25pm, no later), an alarm, and the discipline to lie down even when I wasn't sleepy. The nap is the most generous thing I do for myself now, and I had to fail at it for half a year to learn that it wasn't the nap I was bad at — it was the boundaries around it.