Attitude plays a big role. With a difficult personal or work undertaking, consider all viewpoints, even those you think you don't like. It just might provide relief from your fearful analysis of the situation. Don't oversize the problem which is often a panic reaction. Discuss the actions that you could take with a friend or co-worker which can sometimes provide a good suggestion and some instant stress relief.
Lay out a procedure and slowly complete the first task. The next steps should be easier. Often we will keep on worrying after the decisions are made, which of course is of no help at all. If everything that can be done has been done then it's time to follow through.
"Our plans miscarry if they have no aim. When a man does not know what harbor he is making for, no wind is the right wind." Lucius Seneca (3-65)
Rejection can be an unpleasant experience, but it just lets us know that we aren't perfect. Who is? Consider it a lesson learned, then forget it and move on with your life in a positive constructive manner.
To help solve a difficult problem or to cut down on worrying about making a decision, analyze the situation, determine what must be done and carry it out. In writing or on your PC:
Get all the facts.
Describe the problem in detail.
List all the possible solutions.
List the advantages and disadvantages of each.
Detail what you will do.
You have detailed the planning and know that you will proceed in a certain way, but will review it as required. Later. Now it's time to think other thoughts.
"What we have to learn to do, we learn by doing." - Aristotle (BC)