Well a decent start is to treat the art as a job. Assign specific "art times" during the day and stick to a routine. Keep distractions to a minimum, phones, fb, fa, whatever tempts you away try to limit it when you're in your specified art zones.

Drawing one thing every day, even something quick that you may think looks horrible can help too.

There was a great link about this same issue I saw just recently but I can't remember who wrote it. I just said what I remembered from skimming the article ^^; sorry I couldn't be more helpful

ty im curently on it >,.,<

Attend local life drawing sessions.
Join online (or local) art groups that have weekly sketch jams or art challenges.
Study your favorite artists and try redrawing some of their works to try and get inside their heads and understand why they put that line where they did (just don't post the copied works, I only suggest this as a personal study to help yourself improve).
If you really find you are in a rut try redrawing one of your older images to see if you can improve it.

Hope this helps.

~UBA

Well you could try tying yourself down to a schedule if it works, but in case that backfires, why not just draw 'whenever you feel like it'? Or after every hour of drawing, take another hour or bit of time to stretch and do what it is you want to do.

Set an alarm too, so you don't forget...
And one that goes off and off until you finally pay attention to it...

Motivation is a difficult thing for me, as well. So is being able to maintain proper focus when I work.
One thing that helps me is "white noise". I find certain music tracks that have a certain mood or feeling behind them, which fits into the theme of my work, then I listen to them on low volume on repeat, just so it's in the background. It might not work for everyone, but personally, it not only helps maintain the mood of my stories and work, but keeps me from getting distracted when, say, a television is playing in the background instead. Any lyrics or words in a song can throw me off at times.

If you can find ways to help you concentrate on your art, it can help motivate you to finish it, or even to feel confident enough to start right away on the next one.

Also, I'm sure you have many good friends who are willing to support you and help you out if you need it. Look to them for tips on motivating you to draw and such, too. Maybe they can even directly help motivate you.

Most importantly, find your passion. It sounds weird, but if you draw or write without passion, it can get boring at times and you may lose your drive. Find the thing you love most about drawing, and hang on to that feeling. Remember it as often as you can. Taking commissions can seem like a job, but if you think back on why you like to draw, or what you like to draw, it makes things a lot better.

I hope that helps.