@OP
JFDI is the key. You basically have to choose to focus on something, and do it on a regular basis, to get really good at it. I’ve been running seriously for over a year now, and learning Japanese (Textfugu and RTK) since January. I do these two things virtually every day. I ran – 19 or 20 miles on a couple of days – on a business trip to Taiwan in January. I studied 10-15 kanji a day in RTK for the past 2 weeks while getting setup on a 3-month business trip in Sweden and going sightseeing on the weekends with my wife. There are many days where I don’t do much more than work, eat, sleep, run, and learn Japanese. But you only have so much time no matter what your schedule is, so if learning Japanese is a priority, you have to actually prioritize it over some other things in your life.
As an example: I started playing Go last November. I really enjoyed it, and I had a friend to play with regularly. But I started learning Japanese in January, and after a few weeks I found out that I really didn’t have time for both (and running). So… unfortunately Go had to go. But I’ll get back to it later.. when I can read strategy books in Japanese. Two birds with one stone, but each in its own good time.