Learning to live with the heat (or the cold) ouside is key, I find.
If in the spring you let your body acclimatise, by summer you don't think 80F is all that hot. By the time fall rolls around CelloDad starts looking for an extra layer when it gets below 80F outside. Really!
And set your thermostat where it feels comfortable: DON'T look at the number, ask yourself, Should I set this higher or lower? We tend to settle at 76-78F summer, 62-65 winter. Saves us a bundle on HVAC.