"love casts out fear"... so I guess if you really commit yourself to something then you are "loving" it above all else...and can move ahead?

On another thought, what it is that causes (you) fear? For some it is the fear of failing (rather than try something.) For others it might be fear of a similar negative event recurring (from the past.)

IMO the only time fear motivates positively is when you are trained in whatever it is you end up doing, beforehand. Fear that is reactive rarely has logical thought connected, unless prior training was taken.

I agree with what you seem to show, that serenity is opposite of fear. Be at peace with your goals, and that helps establish them