I am quite curious about the subject myself and read couple of books about it as well. Perhaps the reason behind this is that I've struggled a lot with forming and keeping new habits myself in the past. Hopefully you'll find this helpful in your quest to become more awesome.

About shortcuts

Your brain likes shortcuts. It doesn't have to think which means it doesn't have to apply the prefrontal cortex part of the brain which is the area associated with decision making. It's the most recent part in terms of evolution. In terms of fuel consumption, it's like the Cadillac Escalade. It's hungry!

If you would have to use that part of the brain every time you do something, it would consume a lot of energy and is not sustainable. Therefore the brain wants to automate as much as it can. Shortcuts!

So if every evening for years you watch TV after work and then one day decide that you go running instead, your brain doesn't want to hear anything about that. It wants to do the thing you have always been doing. It's a tried out thing that works and is easy. It's automated. In order to override that automation, you need to use your prefrontal cortex. However, as said earlier, this thing requires fuel. Which you don't really have much after the whole day of working. Your brain's natural tendency to go with easy automated things that don't require any effort is hard to override. Your tank is empty!

This is why it's important to do whatever the thing you want to make your habit as the first thing in the morning. You have all the fuel in your prefrontal cortex. As your day evolves, you use that fuel. Even simple decisions like “what shirt should I wear today?” take up fuel. Apparently this is the reason Mark Zuckerberg wears the same gray T-shirt every day.

The other part of shortcuts is that you need to do the thing every single day. You need to do it so many times, it becomes automated. Your brain literally needs to form pathways and it takes time. Meanwhile the old pathways are very bright and active. You need to not use these old pathways to make them inactive. So every time you decide to watch TV instead, you're helping to activate the old pathways again. Doing the new thing every single day helps to form a new pathway and kill off the old one (because you're not using it).

Lover the bar

One thing to keep in mind here as well, is that it's of course not easy to start exercising every single day out of the blue. Your brain tries to persuade you not to do it. Naturally, going out for a run is much harder than watching TV. A lot more hassle, complicated, takes more energy etc.

The trick is to lover the bar. Think of quantity over quality. Instead of deciding to do all these crazy exercises in the morning like 50 push-ups, hundred crunches and thousand squats and running afterwards, tell your brain that you only do few push-ups. It's much easier for your brain to agree with you on this. Once you start, you may find yourself doing more because of momentum. You're already doing it, might as well do more.

Don't worry about the quality. The action of doing the thing is a lot more important. Once it becomes a habit, it's easier to raise the quality.

This is how I made doing street photography as a habit. Even on the days I did not feel like going to the centre of the city to take pictures, I told myself (still do) something along the lines of: “I just take couple of pictures and that's it. Actually, I don't have to make any pictures, I simply walk a bit and then go home”. I lowered the bar. However, I usually still end up taking pictures.

Key takeaways: do the thing every day, do it in the morning if possible and lover the bar.