Well, it was for me. I actually started HRT as a "test." I had seen the videos on what it could do, read the reports, and the emotions that trans-girls described after going on hormones just rung so true to me... they felt like that was what I had been missing my entire life since puberty. And every single account of how to tell if you're trans or not seemed to point toward me indeed being trans.
So I decided that I was going to tentatively pursue a potential transition, see if I liked what the hormones did for me, and I figured that if I didn't like it, I could just stop them, no harm done as long as it was within the first month or two. So I started a one-month "hormone trial."
They completely blew my mind. They obliterated the mental fog that I had been feeling for my entire adult life.
So now I knew I was going to stay on them. Then the question was, did I really want to do a full transition? Because I still had a LOT of reservations about that. Well, that question was answered when I finally bought female clothes for the first time, bought wigs, and as hormones slowly did their thing, for the first time ever I looked in the mirror and saw a girl looking back at me. It was the single happiest moment of my entire life.
And so I decided to go legit... went to a therapist, got my official letter for HRT, got off of the internet-pharmacy stuff and started under official medical supervision with therapy and the whole nine yards. Started going out as a girl in public now and then, working on my voice rigorously, dieting, and everything else that I believed I needed to do to succeed.
The more and more I've gone out, the more and more people I've come out as trans to, the more and more friends I've made, the more and more often that I've seen a girl in the mirror instead of a guy, the longer and longer I've been on hormones, and the more I've had time to genuinely confront my gender identity after running from it for so long, the more repressed memories keep coming back up. The more I remember how bad my gender issues were before I went into denial. The more I realize just how much repressing them has hurt me over the years. The more I'm noticing my true self come out more and more now. And the more I'm feeling at peace with my body every single day.
Go figure. That's one person's story at least. IMO, when it's right for you, you'll know it. Everything just kind of clicks.