If you haven't seen it, my post on flow may touch on some of this. Let me preface this by saying you should be proud that you're even thinking about this -- I know I was easily 10 years older than you before I started figuring this out. Also, thanks for thinking of me!

The first thing is to not expect yourself to feel any different about the tasks that you have to do. In other words, there's no way to magically make yourself want to do certain things more, nor are you likely to feel better about them. At least not at first. It's about building habits, and fuck motivation. Motivation is the hot girl from the club who makes you think she's interested before she gets bored and moves on. Discipline and habit-forming is the girl who comes over to take care of you when you're sick. There are times when I'm literally saying in my head over and over some mantra of "I hate this and don't want to do it," while doing it. That for me is helpful - it means I can put more energy into doing it than into trying to make myself happy about it. I think we get off track (or at least I know I do) by thinking we can change how we feel about something in order to make it easier to do. I don't think that's true; the feelings come second. First you just have to decide you're going to do it even though you don't want to, and even though you may not be happy while doing it. This Zenpencils comic (using a quote by one of your countrymen) is also good.

Some people find scheduling helpful, and it definitely can be in terms of building those habits. I think at the end of the day it's about accountability - what's keeping you from slacking off? Having other people can help; it both makes the task less unpleasant and can be a strong motivator in and of itself. When I first started lifting weights in law school, I never would've worked half as hard as I did if I hadn't had someone to go with me. We weren't even super close friends or anything: I'm a hippy, anti-establishment, vaguely-pacifist guy, he is a Mormon who had recently become an officer in the Marine Corps. But we kept each other on schedule, and the result was that over the course of 1.5 years I gained close to 50 lbs. of muscle (I was that underweight when we started). Nowadays, knowing my kung fu school is there training gives me a big boost in forcing myself to come in, and it makes training much more enjoyable than it would be if I were just sitting on my own.

The other thing I'll mention is that you need to have a balance between short- and long-term goals. Long-term goals are why you start, but then you need to put those out of your mind. Or at least I do much of the time. I think that's been one of my problems with drawing - I can see what a good picture looks like, so all I see in the meantime is the difference. This gets into what I wrote about in the post I linked above: the need to find short-term goals and work on them, but have them be in service to the larger one. It also makes things less overwhelming. If you're training to run a marathon, you shouldn't spend all your time thinking about the marathon; it just gets too abstract. Instead, think about building up to running 2 miles. Then 3, then 4, etc. Eventually you're there.