Check out "The Renaissance Soul: Life Design for People with Too Many Passions to Pick Just One".

I've read this book several times and it really resonates with me. I have a lot of varied interests (sports, crafts, community, work, science, technology, programming, writing, home, family, music and on and on) and as others have mentioned I can't move them all forward at once. However, I do want to capture any thoughts I have about them and I do want to be reminded about them enough to recognize an opportunity when it arises. And you will notice that as you use your Someday/Maybe list (aka, review it regularly) opportunities will arise!

The Renaissance Soul suggests choosing three to five areas to focus on at any one time, scheduling time for working on them, and putting the rest on the back-burner. The catch is that you can change them at will as your interests change (or seasons, or whatever). For me, this happens during the weekly review - "Hmmm, anything I need to be doing about oboe playing? Nope, I'm good. What about golf? Oh yeah, I've got to renew our membership" Then I add to my @PersonalAnywhere list: "Print golf membership form from Nov 15 email (due Jan 15)"

I echo the suggestion to start your GTD journey on paper - writing your lists and seeing them and turning the pages from one to the next can help cement the GTD processes and help you see what contexts will work for you.