Good post, I've been lifting for ~3 months now and I can definitely agree that the mental changes are dramatic. More than anything, that feeling of being strong makes you want to be stronger in other aspects of life and discipline yourself more. My biggest struggle has been my drinking problems but I no longer feel defeated at the end of the day. When I go to the gym I can't help but think, "fuck dude, you just picked up 200 pounds, surely you can put down a bottle".
I'm finally trying to get my diet in order, and I have no doubt that it is because I am still succeeding in my current lifting routine.
I know lots of guys talk about getting your house in order before starting to lift, but I have to say, there is something simple about gritting through that first month of it that makes you want to be better in everything. It's like, everything else seems trivial compared to what it takes to keep pushing that bar up. Just my 2 cents about what keeps me going.