When God's Word says "fear not," this command is often directly paired with an assurance that makes it possible: "Fear thou not, for I am with thee"; "It is I, be not afraid" (Matt. 14:27); "Fear not, for I have redeemed thee" (Isa. 43:1). There is much to be afraid of in this world, and simply setting that fear aside is mere bravado. The only way to be truly fearless is to trust implicitly in Him who is greater than all fear.
The disciples panicked in the storm because they didn't fully realize Who was in their ship (Mark 4:41); if they had, they would surely have known that whatever a storm might do to them, it could never overcome Him. When we face our own storms and our own fears, as we all will, we can hear His voice telling us to be of good cheer - not necessarily because everything is about to change for the better on the outside, but simply because He is with us on the inside.
All Scripture references from KJV. Commentary ©2011 Hitchcock Family Ministry. Unaltered text may be reproduced freely without financial gain. Original commentary and Scripture song available at http://www.freescripturesongs.org/fear-thou-not-for-I-am-with-thee.