One of the ways to make sure a change in your life sticks is to make what you want to do so easy to do, you can't avoid it. Another way is to adjust your environment so that going back to the old way is more difficult.
Not given to easy solutions, I suppose, I opted for the latter.
I've now started my first semester as a doctoral student at UNC-Chapel Hill's School of Information and Library Science (SILS). I was 12 hours from finishing my master's, but it was clear to me that the master's wasn't going to help me; I was going to stay where I was, career-wise. Unlike my friend Mike, who'd gotten his MBA in the same time period and thus had both the sheepskin and the experience, I would have only had the diploma with no relevant work experience or internship to back up the education.
But I saw that I loved the campus environment and was good at this type of work. I also found very encouraging support from fellow students and key faculty. And some opportunities came my way that I did not want to ignore. So, for many many reasons too numerous and tedious to list here (though "100 reasons I'm in PhD School" would be a good topic for a post), I opted to make some severe changes in my life.
The most critical one was to leave my full-time job and drop down to about 10 hours a week--enough to cover my weekly car payment and provide some spending money. I also helped to interview and train my successor. The finality of my decision really didn't hit home with me till we started interviewing candidates: someone else will have this job and, if the school thing doesn't work out, there's no going back. That's when this whole adventure started getting Real for me.
(This may be because I'm from a generation and upbringing where Having a Job is the primary sign of worth and usefulness to yourself, your family, and your self-esteem. Not having a Real Job is just strange and odd to me, like looking at a picture of myself printed backwards.)
The image I use to describe this to people is that of a ratchet: turn the ratchet, it clicks past the notch--and can't turn backward. The ratchet only turns one way. Likewise, I've made changes to my environment such that I can only move forward; I can't go back. And while it's a little terrifying, this commitment is a good thing for me. I've left jobs before without a second thought, because I was fortunate enough to have some safety nets in place--my parents, The Beauteous Liz--and I was confident I could find another job in the local tech-writing field if I needed one. My skills were portable and I had the freedom to go where I thought the jobs were the most interesting (though after 4 years at a place, I was always ready to leave and try something new).
In this case, I am my safety net. Liz is still there, of course, as is our house, our friends, etc. But there are hardly any tech-writing jobs out there nowadays, and the good times are past when the table was so full you could live off the crumbs. This, among many many other reasons, was why I made this choice to take the fellowship and invest in myself now, rather than wait. The wave was cresting, and I wanted to ride that current as it moved downstream rather than continue to paddle and waste my energy trying to make it back upstream. And the commitment that this racheting effect enforces is important to me right now. There's no easy escape hatch back to my old life -- it's up to me to make this work. It's a challenge I feel ready for.