Not sure how helpful this is, but I make a list of all the most pressing things I want to learn and everyday I'll look it over and choose whatever I feel like doing for however long I want.

The point here isn't efficiency, this is basically the bare minimum I think one can do while still learning and making progress, i.e. you don't need to follow a rigorous schedule or cultivate a great deal of self discipline if you enjoy the task. Doing even 20 minutes is always better than nothing at all.

Do this and slowly build up discipline by pairing it up with consistency.