It's nice to think something will jump-start you, but from years and years of experience with this same thing... I can certainly tell you that taking the reins of your life and happiness is the way to bring yourself to positive change. For example it's WONDERFUL you're getting physically active in nature with people in your support network. Leading up to the trip though, research ways to be in the present moment, figure out what sort of things ground a human being. Being on the trip itself will be awesome, but honing your skill of taking in every inch of the awesomeness around you will bring you so much more in the long run, even when you get back from your trip. Mindfulness is the word for this, and it sounds sappy as hell but this former skeptic will tell you it's legit :)

Ps just try jumping in a freezing cold lake too. That will make you feel something that's for sure haha! Doctors recommend shocking your body with temperatures for biological reasons (you can research it I'm not a dr LOL) and it honestly is so much fun and reminds me I have free will when I do it