Take a day for yourself
I think its really important to take time to celebrate wins with GTD. Its one of the things that will keep you working the process. Early on those wins may seem small (like the first time you get in to empty) but you should celebrate those small victories.
After a year of GTD I think there are probably a number of things you could do. A party could be good but if a major project is in the health area, I'd recommend designing a party that is in alignment with that goal rather than an being an exception to it.
A high-level altitude retreat is also a great idea, though you should probably do this anyway.
I recommend taking a day for yourself. Go ahead and take the day off of work. Either spend the day doing fun, creative, or entertaining stuff that isn't on your lists, or pick a really fun project that's either active or on your someday maybe list and play with that.
Just have fun and consciously recognize that you are rewarding yourself for all the advances you've made with GTD.
Congrats on the first year!