You have absolute control over but one thing, and that is your thoughts. This is the most significant and inspiring of all facts known to man! It reflects man's Divine nature. This Divine prerogative is the sole means by which you may control your own destiny. If you fail to control your own mind, you may be sure you will control nothing else. p. 173

You have power over your mind—not outside events.

You have power over your mind – not outside events. Realize this, and you will find strength.

Mind control is the result of self-discipline and habit. You either control your mind or it controls you. There is no half-way compromise. The most practical of all methods for controlling the mind is the habit of keeping it busy with a definite purpose, backed by a definite plan...Without this control, success is not possible. p. 173

Be able to turn my mind on and off at will.
Master it rather than be enslaved by it.
Control the arrival and departure of thoughts.

You have two choices, to control your mind or to let your mind control you.

Control of the mind can be achieved by understanding yourself, the aim and the energy which is blocking us from progressing. Between God and the Self, the blocking energy is the ego.

Mind control is the result of self-discipline and habit. You either control your mind or it controls you. There is no hall-way compromise.

if you make the decision to master your own mind, you’ll be mentally equipped to handle whatever challenges come your way.

Ultimately, the only way to truly be in control of your life is to be in control of your thoughts.

To enjoy good health, to bring true happiness to one’s family, to bring peace to all, one must first discipline and control one’s own mind. If a man can control his mind, he can find the way to Enlightenment, and all wisdom and virtue will naturally come to him.

(…) A weak mind cannot control its own projections. Be aware, therefore, of your mind and its projections. You cannot control what you do not know. On the other hand, knowledge gives power. In practice it is very simple. To control yourself – know yourself.

To enjoy good health, to bring true happiness to one's family, to bring peace to all, one must first discipline and control one's own mind. If a man can control his mind he can find the way to Enlightenment, and all wisdom and virtue will naturally come to him.

You are not in control of your mind — because you, as a conscious agent, are only part of your mind, living at the mercy of other parts.15 You can do what you decide to do — but you cannot decide what you will decide to do. Of course, you can create a framework in which certain decisions are more likely than others — you can, for instance, purge your house of all sweets, making it very unlikely that you will eat dessert later in the evening — but you cannot know why you were able to submit to such a framework today when you weren’t yesterday.
So it’s not that willpower isn’t important or that it is destined to be undermined by biology. Willpower is itself a biological phenomenon. You can change your life, and yourself, through effort and discipline — but you have whatever capacity for effort and discipline you have in this moment, and not a scintilla more (or less). You are either lucky in this department or you aren’t — and you cannot make your own luck.