For every action, there is an equal and opposite reaction. When you choose to step out and add movement into your life, I guarantee there will be a response. A lot of times, it is from others. Peers not appreciating your change, scheduling difficulties, outcomes that don't manifest as quickly as expected, all of the things that stop people from motion. Stop people from change. The inertia of life. And if that is not the case, then you may get a reaction from within yourself. Self-doubt, self-consciousness, self-evaluation. The origin of these responses range from physical, to spiritual, to emotional. The only way to combat them is what got you here in the first place: Action.