I know I can't be alone in this, but it makes me feel so weak and powerless. Is anyone else paralyzed by choice?

I've never been terribly clear on what I wanted to be when I grew up. My passions have always changed with the wind, and I've made the mistake of listening to advice—really, really, spectacularly shitty advice. "Just stick with something so you can graduate, already!" "Don't go into creative writing, there's no money in it. Go into JOURNALISM!" So, I went with #2 and did #1, and now I hate writing. Journalism killed my love of creative writing.

I mentioned to another GTer that I have semi-annual existential crises, and I've been in the thick of one lately. I figure if I'm constantly questioning my life choices, and it's become physically painful to go to work (headaches, neckaches, backaches, that throbby feeling in your brain from the impending rage aneurysm, etc), it might actually be time to do something about it.

I currently work in sales. I strongly dislike sales, and inside sales even moreso. Guess what I do. I want to get into environmental sciences. I have a strange fascination with compost, and nothing would make me happier than discussing worms and poop all day (yeah, this is the real me, folks). Natural methods of water filtration, geothermal heating, hydroponics, aquaponics, rooftop gardens! THAT'S the stuff I want to sell. THAT'S the stuff I want to talk about all day.

So, that's what I've decided to go after. I've spiffed up my resume, but nothing on there indicates that I have any experience with environmental science... because I don't. And my husband's education doesn't count. Would it be smart of me to try to get a sales job within the industry to see if I like it, and then take classes? Or should I stick with the job I have and take classes first? This is the part I can't decide on.

How have you made a big life change? What inspired your decision? Was it worth it?