Day trips to go explore this weekend

So: I hate the vibe of south Florida, I desperately miss living in Boston, no I can't move. I'm going through an insane depressive funk and I need to get out of here and go do something anywhere this weekend, but I don't know where to go with a very limited budget. I don't like beaches and am not very athletic, but honestly I am open to all suggestions: I just need something transformative, different, something that will make me enjoy life again.

a) I'm craving somewhere walkable (a city, a walkable downtown, anything). Somewhere further away/kinder (?) than Fort Lauderdale or Miami

b) I can get to in an affordable way - I can drive (~3 hour max from Boca) or a destination I can get to via Tri Rail and won't need a car in

c) Safe & comfortable to be in alone - I'm a woman in my twenties & grew up very sheltered and isolated & have never actually solo traveled before so I don't want to be reckless