Some might say dedication, commitment, etc, but I think in reality it usually comes down to two things: (1) a strong interest in your chosen topic, and (2) a very boring desk job where you can get away with updating your personal blog and passing it off as work.
Hm. I certainly have a strong interest in yoga, but I have a job that seriously keeps me busy. Granted, I’m only working part-time, but as soon as I’m home, I’m usually distracted by other things and sitting down to write seems like an inconvenience. I think the best solution for me is to plan on staying in my office after work every day just to write for a little while. I’m not obligated to work, and there’s not much to distract me as long as no one’s around. Perfect.
P.S. Any other ideas?