Be in an environment that is conducive to learning- without music, background noise, or other distractions. A beis midrash or kollel is a great place to learn seriously, and maybe you should get a chavrusa or rebbe to keep you on track.
When I am hearing kol Torah, and watching people involved in the milchamta d’torah, that usually excited me enough to forget everything else. Torah cannot be adulterated or mixed up with concerns or other thoughts, it must be central and you have to want it.