San Diego is pretty hilly. Some of them can be quite steep. I'm at the overlap of "very good" and "excellent" on Coggan's w/kg chart and I find myself having to produce > z2 levels of power and heart rate at time to time. I just don't mind it too much and try to take it easy on hills for the most part when endurance is my goal.

Or ride the trainer. I'll do (up to) 3-4 hours on a Zwift C or B based group ride pretty regularly, especially in the winter when it is not 70F and sunny . But I do have a pretty amenable setup in my garage.

(stock photo of the garage pain cave - usually a road bike on there)