The chain method (Seinfeld productivity secret) really does work. Have you tried it?
I have used the chain method to good effect. In fact, I am using it right now. I do recommend it, BUT...
I think it's fair to warn that it's an integrity-based method. In other words, you are putting more at risk than the imaginary concept of the chain. There is something very real and very important at risk: your personal integrity. The chain is not just a chain; it is a line in the sand; it is a glass wall. There's nothing keeping you from crossing that faint line but yourself. If you do cross it, the glass wall shatters, and you can't put it back together again -- it stops having any power to stop you. The chain, that wall, is your very integrity. Every time you cross the line, and inherently reward yourself in doing so (or you wouldn't have been tempted to cross it in the first place), it becomes easier and easier to cross the next time. That's human nature.
In other words, the danger is that it stops working after breaking it. It's not a matter of merely building another chain. (Though, curiously, building chains for other things can still work.)
That's why I think it's important that there's a built-in leniency in the system. Missing one day is undesirable, but not the end of the world. Life happens. You aren't risking your integrity on one day. But missing one day means you go into emergency mode. Stay up all night if you have to, but get it done. Then you're safe. (Chaining works better for doing something than avoiding doing something.)
Anyway, I recommend choosing something relatively EASY if you use the chain system, because I guarantee you, some days EASY will seem HARD, and HARD will seem IMPOSSIBLE.