I found that as soon as you have a meaningful task, you won't struggle with motivation any more. I've always tried to find side-projects to work on, with or without income doesn't really matter, as long as you're being part of something that's more than just "time-filler". For example for some time I was super interested in LED-stuff, so I got involved in an LED forum/community and all of a sudden I was super motivated to learn Arduino-Programming, to help other people in the forum as well as being able to present them my work. This interest later even got me some money on the side when I did some jobs for a garage (install LED lighting in cars). Currently I switched from Arduino to RbPi-Home Automation, but the principle still applies. Find a project that you're really interested in, try to get involved with other people with similar interest and you'll see that motivation will keep up.