Things get easier when it becomes habit. I’ve found that it becomes easier to write if I write at the same time each day. It’s as if my body expects it to happen, and my mind gets in the right place. I’ve read strategies and habits from different successful writers, and something keeps popping up. They all write at the same time each day, and they all write in the same place each day.
I've played around with different approaches to remain constant in my writing. I've tried writing for time, word-count, and most recently, until I felt as if I accomplished something. Personally, I don't think any method is superior to another; however, try them out and see what works. I read a blog post by Chuck Wendig (check it out here) that said if you write 350 words a day for 260 days, by the end of the year you'll have over 90K words. 350 words is nothing. Find what works the best for you and stick with it. If it's word count, great. If it's time, get out your stopwatch. If it's until you feel good about it, wonderful. Whatever works, works. Just keep at it and keep it consistent.
The bottom line -- it’s about getting words out first. The magic of revision can come later and should come later. Spew your rough draft out and then pick the quality pieces out of the primordial ooze.