A trick is to set yourself multiple tasks that are not exciting, so that you do at least one. If I tell myself, "I will edit all the photos I have been taking for almost a decade", I may not get around to it.

So, I tell myself, "I will either edit photos, vacuum the house or read the iOS Human Interface Guidelines." Then I may bounce from task to task, but I will finish at least one. After a while, the irritation of leaving a task half-done drives me to complete the other tasks as well.