Team buffer here.
Here's a break down of somethings that may help
Shorter Stories: Try doing a one shot comic. Everyone thinks everything has to be an epic saga, but if you are honest with yourself and you don't see yourself committing to a full story try shorter stories. So maybe start with 10 page as your goal, then bump yourself a little bit more every time. 24 pages is the standard dounjin/comic issue size and back in the day before manga people use to tell a complete story in under 30 pages. You'll feel more accomplished knowing that you finished something versus struggling to finish something too complex.
Try gag a day or one page a day comics If you have many ideas and can't focus on a full story you are possibly more suited to doing a gag a day comic, or one shot page stories. Set up a cast of characters and a vague premise where you don't have to commit to a story. Then it's just a mini adventure or thought of the day, conveyed in a few panels.
Set aside comic work day: Set aside a comic day, so times when you know you have down time and try to stick with it. Easier said than done because games and tumblr is tempting but you got to do it.
Get a friend to keep you on schedule: Whether it's in real life or online get someone else who is a comic artist OR someone who is maybe more focused and tell them to make sure you commit.
Work together with someone: This ties in the previous. Online artists can work (If you set up a livestream or something) although in person is better. Set up comic work dates with another artist. Artists get creative energy and inspiration from each other.
When you are motivated keep working: Whenever you feel motivated use that opportunity to pump out as many pages as you can. Don't stop your momentum because you feel you've done enough. Ride the inspiration train when it comes.
Work in sections: Instead of trying to complete a whole comic page try working on it in pieces. So example let's say you are a doing 10 page comic. Do 10 sketches, then start over and do the lineart for the 10 pages, then come back again and do the shading/coloring. For me personally this helps me out because doing an entire page takes ALOT of energy out of me, I can't do a whole page in one go anymore. Some days I feel like doing sketchy guidelines and then other days I feel like doing lineart and so on. I even skip my backgrounds and come back to them later because those are a pain to spend any effort on after you draw characters.
Be on schedule that works for you Everyone's schedules work differently so you need to decided how often you can update. Like what everyone has been saying, draw pages up in advance and queue them up and upload them over time. Don't upload a bunch of pages at once and run out of steam. Readers can wait, you just need to be consistent.
As for inspiration: I personally read other webcomics and comics I like. If you can turn envy into motivation you'll be very productive and motivated.
Reward yourself AFTER you do work I personally pace myself, so I'll work for 1 hr, then goof off for 20mins then come back and work. No need to work for a long time, just try to pace yourself, but don't get carried away on your breaks cough.
Hope that helps 
