You try something completely new that's also creative be different subjects to draw, new mediums, or even completely different art fields to get into the creative mood.

Start carrying a sketchbook with you wherever you go.  When you have breaks at your job or anytime you have a free moment to yourself, sketch stuff.  Idly sketch whatever's around you.  Doodle things.

If all you have is time after work, join some kind of amateur art group.  Take a life drawing class or workshop.  Join your local Urban Sketchers group or go out for Sketchcrawl.  Join a local comic creator group.  Whatever forces you to actually go out and tackle things outside of your comfort zone and be accountable to people while letting you see that not everyone in the world is some kind of rockstar pro artist.

Drawing is hard, so you need to put yourself in situations where you have few distractions and a reason to keep doing it past the point of discomfort.  At home you have a ton of distractions and you have little reason to continue to draw after the first few minutes, so the moment your brain starts thinking "this sucks", you quit.  If you pay money to show up to a workshop or you take the trouble to drag yourself out to a group, you feel like you have to produce something, especially if the group is going to look at everyone's work afterwards. 

When you've taken some trouble to get somewhere, you can't just leave, because then you'll feel like you've wasted money or time.  So you feel obligated to stick it out past the "this sucks" point, and usually after you get your brain to stop whining and complaining you can have a pretty good time.  And if the group is supportive (as real life art groups often are) and everyone says "this is nice" or "I like the way you've done X" then you get to feel a little bit good about your work and it makes you want to come back.

It might be hard the first time, so tell yourself to stick it out and go at least 3 times.  If the group is really critical then try a different group (unless you like the criticism, of course).  Getting out to new places and socializing with people can be a really good way to get yourself out of a rut.

Once you get used to drawing from life and/or doodling, you'll find it a little easier to tackle more complicated artwork at home.  Backgrounds won't be so intimidating if you've gotten used to drawing streets outside.  Figures won't be so intimidating if you've gone to figure drawing.  Being able to ask other artists questions is often useful and they'll give you ideas for things you can try out.