What do you think is the opposite of fear? That's simple. Wisdom. Fear only exists when one does not know. When one knows and truly grasps that knowledge, they achieve wisdom and fear becomes an impossibility. You cannot be afraid of what you do know.
It depends on the type of fear: If you have a fear of death; there is no sensible opposition to this since the object of the fear (the reality of death) is real, and will remain real until the death itself becomes avoidable. But if your fear is restricted to the situations such as "being alone" or "loosing financial freedom", etc., the opposite could be diversification of resources, or working more to get more or any other constructive strategy of your choice. If your fear is about an assumed idea, such as God or system, opposite to this situation would be just "relaxing", both physically and mentally. How? start a new thing, find a partner, separate from partner, have a laugh, devote yourself something new and something makes sense. Fear is the result and alert of the mind. In most cases, we are alive or successful just because of our fears. We simply do not need the opposite.
You could say bravery oppses fear, but one must be frightful to be brave. There is no opposite of fear, only hope&faith which trumps fear.
The opposite of fear is desire. Fear will generate fight or flight. While desire causes one to become attracted so there is a bond. f you have two people that are afraid of each other, the result comes down to one, due to running or fighting; subtraction. With desire two becomes three; addition. The opposites of fear and desire are minus and plus.
I once desired a woman... every day I would fear not obtaining her, sorry sir, you are wrong. Desire, and fear are fairly similar.