[loungin]

This might sound weird, but test yourself in the morning. Do you wake up ready to get to work? Or does the thought of it keep you in bed for another hour after the initial alarm goes off? Seriously, that is how I know I like what I am doing. Do keep in mind that there are always the bad days, so do several self 'tests'.

For me, personally, the lack of learning or something challenging would be the deal breaker.

PS - And since you are near/in SF, take another posters advice and do some hiking in desolation wilderness near Tahoe's south shore. Mt. Tallac makes a great day trip and it's easy to get to with a fantastic view. (Contrary to the name, it is beautiful.)