Want to help me figure out how to figure out what I like to do?

Don't be so hard on yourself, you've listed at least three interests. If I were in your position I would consider doing two things: joining a bookgroup and making some kind of project out of taking walks. For the first, I'd look at the local independent bookstore to see if they have a series of bookgroups you could look over and join. This combines reading and meeting people. You might also check at the local library if there isn't an independent bookstore near you. For the second, I'd consider where you like to walk and make up something to get you doing more of it. Do you like to hike in the woods? What about traveling to hiking in all of the state parks you can get to from where you live? What about visiting every cuty park? What about exloring on foot a new neighborhood each weekend? What about getting a cute dog to take on walks and attract earnest affectionate boys? Other than that, is there something that you've wanted to try before that you've felt like you didn't have time to do? Yoga, Pilates, pottery, painting? Learning Spanish, cooking? Now is the time to pick something that isn't now a hobby, but which you've been vaguely interested in before, and pursue it. Eating creates the appetite.

Take up a martial art. (See also: "http://ask.metafilter.com/mefi/20218" and "http://ask.metafilter.com/mefi/27735".)

I got a lot of good suggestions when I asked a very similar question http://ask.metafilter.com/mefi/9350

I think trying a few new things helps with working out how you want to spend your free time. I found the weekly newspaper brought to my attention some new interests. For exercise I do Bikram yoga and walk.

Take a class in something vaguely interesting to you. It's a great way to discover what you like, meet people who also have a certain amount of free time, improve yourself, and maybe a gateway into an entire new interest. Plus it's a commitment of a few weeks, after which you can decide to go further or try something else. If you want, you can take a dance class - different types of dance use different amounts of energy, but it could potentially help you with the fitness issue.

I could stand to lose about 15-20 pounds Then obviously you need something that isn't sedentary. Stay away from the kitchen, out of the house, out of restaurants, out of your seat. Keep sky above you and you'll lose weight and be happy. If you're in the Northern Hemisphere, it's spring, time for biking, hiking, running, swimming, sailing, climbing, camping, gardening. Join a club that does one or more of these things and you'll have more fun and meet people.

I second the Red Cross. It can be a lot of fun. You know what I did last time I was single and feeling miserable? I sat around, watched TV, surfed the web, and downloaded more porn than you can shake a stick at. Then I said "This has to change." - and I picked up my iPod, my camera, the GPS, and went http://www.geocaching.com. I personally think that getting up and getting out of the house is very important. It's also a great way to meet people. Maybe you could start a local Geocaching group or join one that already exists? http://www.mixermixer.com is a way to meet people too. It's not a dating thing, just a "random people that hang out" setting. (Might be just a Bay Area thing, tho..I'm not sure)

A friend of mine went through a similar situation and she ended up taking breakdancing classes, which seemed to help her take up her time, lose weight, and meet single guys.

This may sound kinda dumb, but... Theme nights. Monday - go out to a movie night Tuesday - yoga night Wednesday - etc. etc. etc. The specific events and nights are entirely up to you, but if you schedule something for the same night every week, the cool thing is you can make an event of it - tell your friends that every Monday's movie night, and people will come along with you. Before you know it you're going out with a group of people at least once a week. The only way to discover new interests is to try things - if you like it, it's a new interest; if you don't, it was a good experience anyway. I'm happily engaged, and will be happily married next year, but damn I loved being single. It's a lot of fun, doing whatever you want. Remember, there's no success or failure here, just degrees of success. There are no wrong answers. Go have fun!