A big challenge can sometimes be scary and overwhelming. The bigger it is the more impossible it seems and the more chance of getting analysis paralysis to kick in where you wined up doing nothing about it. Like deciding to clean a house after a big party, you don't know were to start. If the change your wanting to make is so big it doesn't allow your emotional brain to act why not shrink the change until it doesn't scare you. If the change is your career, why not devote 20 minutes a night on something on the side, if it's getting in shape why not just start by lifting weights 10 minutes a day.
By shrinking the change it will help you act on the first move and who knows; One move may lead to the next.
