My suggestion would be to find one subject that really grabs you- that you just can't put down.

Something that lights a kind of fire in you.
If you can find that thing, you won't need much motivation beyond that.
I have found a couple things that I am drawn to even in my darkest periods because they simply fascinate me... though it isn't always terribly obvious for everyone what those things are.

A fairly simple way to explore with little commitment and low-level of initial effort might be to go to wikipedia and start clicking the "random article" button.

It sounds maybe TOO simple, but it will give you a large array of subjects and interests to hit upon. Eventually something may light you up and entice you to investigate further.
And that's what learning is- investigation.
You can build on that initial curiosity and go on to read, watch films, talk to people, all kinds of things.

But you have to figure out what will create that special spark, yeah?

I feel like learning for the sake of learning is always great, learning something you LOVE is a great experience, though, and a perpetual reward.