Any recommendations for beautiful quickie hikes in the Bay until I'm back to normal?
For beauty, you can't miss with Muir Woods. Big redwoods and fern gardens are the Bay Area's best for nature. Although you have an entrance fee, then the many tourists. Big Basin also has some good trails, and I would suggest bike trails as you can find them. I like urban hiking in SF, there's Twin Peaks via Market Street, and we used to do a loop about the city center, to the Civic Center, Wharf, Chinatown, North Beach, Financial District, and then the Embarcadero (5 miles).
I only go for uphill exercise, namely peaks (bumps), but the Bay Area is great for walking. If you suffer some problem from exertion, medical help is right there. And if you bit off more hiking than you can chew, mass transit is excellent (by most city standards) to get you back to your car or home.