Hey, don't pay any attention to the time/your age. I decided in 1967 what I wanted to study, my passion, but changed my major in 1970 and got a degree in a wholly different subject (1972) and finally got my degree in the "right" subject in 2007!
Decide you want to do this, are going to do this, however long it takes, however hard it is, etc. and then just work on it. One thing that has always been hard for me is having a goal and eventually getting there and then what? It's scary having something "finished" and having to look around and find something else to identify with? The older we get the harder I think it is, too, because we have already done most of what we wanted, tried what we were interested in, etc. so there is less and less out there left to do? But I am beginning to trust myself to come up with something, in my own time that fits me.
You have any environmental areas you can/would like to volunteer at? Check out your county's environmental page (mine below) and use something to get your juices flowing again:
Harford County, Parks & Recreation - Nature & Environmental Programs