Conclusion

Do stuff. Be happy.

A word of warning

It's easy to get too interested in GTD. Initially, it's natural and expected that you'll spend some time trying out different ways of doing things, and various tools and approaches and so on. However, this should not become a primary occupation. The goal is not to have GTD as a hobby, since that'll just get in the way of actually doing useful things.

The irony of the previous paragraph being written by someone who wrote a booklet about GTD is duly noted.