The only way to keep growing is by challenging yourself. Work on some project, subject, style, method that you're unfamiliar with. Get out of your comfort zone. Shake things up. And you have to work from inception to completion. Leaving a bunch of open-ended projects can be detrimental to your ability to succeed. You need to start with a goal in mind and fulfill it. Even if the result isn't exceptional. If its not good enough. Do it again. That's how you grow.
Motivation is a very different, personal thing. What motivates me may or may not motivate you. You have to find the fire somehow and it really depends on your personal situation. I spent a lot of late nights working on things so I could get ahead as opposed to other friends doing "fun" things or wasting time.



Photoshop, FTW!