A routine that works
After trying several productivity methods, I finally found/adapted one that actually works. The key is to keep it lose so that it’s easy to restart in case of failure.
First, buy a weekly planner like this one. Every Sunday night, before going to bed, write down what you want to achieve, what new habit you want to form, or what new goal you have in mind. You might have dozens of projects, but just pick one – any one.
During the week, try to keep the habit going. If you fail one day, that's okay; you still have six other days to catch up. If you fail the whole week, you can restart the following Monday.
Evaluate how you feel about your new habit every Sunday. If it seems too hard, just move on and try something else. If you think you need a couple more weeks to make it stick, keep at it. I usually want to try new things every week, but the previous habit sticks.
This method worked for me because I'm a perfectionist, which is not always a good thing. Sometimes, I put things off because I want to over-plan them so that they're perfect. With the weekly planner, I just GO and do them. After all, if they're not perfect, I can refine them the following week.
Also, sometimes it's discouraging to lose your streak (if you're trying to keep monthly or yearly goals). "Yeah, I did that for six months, and then I had to travel and lost my streak! I'm not going to do it anymore." With this method, I have two opportunities to restart: one every day and another every week. If something isn't working after a couple of weeks (like getting up at 5 a.m. and running six miles), I just remove it and try the next thing.