A suggestion
I've always had a terrible time formulating longer-term goals... so I rarely bothered. But GTD inspired me to try because I can clearly see that being able to align my tasks and projects with those goals will help me get there. The question is what those goals are.
Mindmaps don't work well for me and while Bonsai is perfect for NAs and Projects it's I find it rotten for brainstorming (I don't think in outline form). Staring at a blank page or trying to make categories (health, finances) just gave me a headache. But after several false starts, I found a technique that at least got me going and that I thought I might share.
What I did was open up a document and type, "In ten years I will be 44, (husband) will be 48, and (kid) will be 13."
Then I started writing, in prose, what I want to have/do/etc at that time in various areas of my life (no headings or real organization, just prose). Things like "I want to live..." with a description of my ideal housing situation and "I want to work..." with information on my perfect job. I kept it to a high level --not house at (address) or even house in (neighborhood), but more like house with large yard, good schools, etc. I also included things I don't want.
Then I skipped a step and wrote, "In five years I will be 39..." and so on.
Then I retyped the original things that still applied, but adjusted them for the time frame. So in 10 years I want to be working for myself on a path that aligns with my life purpose. In five years I will settle for working for myself (since I don't know my life purpose). And in three years, I want a good paying job with lots of flexibility and no travel or major commute.
I went all the way to next year (10, 5, 3, 1 years).
My next task is to create some projects from these things and I can already see how that might be done. Some projects will be nebulous (Someday / Maybe) and not ready for NAs yet, but others will be. There are things I can do right now that lead to the life I want in a decade. And that's pretty exciting.