Lived all over down there in my 20's Costa Mesa, Laguna, Marina Del Rey, San Diego. My sis still lives there.
The fitness lifestyle is great. It's not actually just fitness, it's whatever you want, some people do dope and party, some surf, some join cults, some gang bang. LOL And some do fitness.
The rest is rough. Driving sucks bad. Housing is the most expensive thing. Anywhere near water is super expensive to buy or rent.
To rent and live on one income and live simply, normal car and such, you could probably get by on 80k. But that won't put you near the water.