This is a question I've been struggling with. I don't think I will go for a Ph.D. Right now I'm looking into bioinformatics programs (MS). My undergraduate degree is in biology and while I was there the plan was vet school. I didn't apply right away (actually I still had 2-3 pre-reqs to take) and worked in the field for five years. I decided that's not what I want to do anymore. (I actually went through a half-@$$ed application cycle because I knew I would regret it if I didn't).
I've always loved two things: biology and computers. Bioinformatics is what I'm looking into now for that reason. I found an online program that I could do part time and still work full time, because my situation right now does not allow for any other options.