How so you guys motivate yourself when starting a side project/learning new language/technology? I am having some problems sitting down and working on my own stuff :(

Just rest if you feel like it so you don't burn out.

You will work on side projects when you feel like it

Mostly it's this great idea or a goal you want to accomplish that gives you the drive.
But the longer/hard/boring a project becomes it might help to setup a todo list with small simple steps.
This way it's not hard to stay focused and keep working on it.

Some say break it to as small a piece as possible and just do bits by bits. You need a function that only does something benign, add it to a list.

Likewise, what do you do if you really want to start a side project to practice/learn something, but can't come up with anything to actually DO for the side project?