I'm glad to see this article on Hacker News. I started lifting weights way back in High School for the same reason most people start - to get girls. I went through a long cycle of going hard for 3-4 months and not lifting at all for 3-4 months. It took me a long time to realize that it's much more effective (as in it actually works) to go medium for all 12 months out of the year.

The most important bits of advice I ever got came from an ex-Olympic weight training coach: don't rely on a partner to spot you and motivate you and don't make the workout so hard that it's not enjoyable. The former is important because your motivation is not tied to someone else's. Over the years I've had weightlifting partners come and go, but in the end my success has been tied to my own motivation. The latter is really the key: if you go extremely hard and kill yourself working out, this will be what you remember on the days you don't so much feel like lifting, and ultimately it will cause you to procrastinate.

Consistency is the most important thing, not intensity. Once weight lifting becomes something routine that you "just do" every day, and not part of some major life changing period of your life, it starts to work.