The entire recruit process is a preparation for your career. It is a long race, so do not burn yourself out on the first lap. A police career is like designing and building a building. What you bring to the job is your family upbringing, education, life experience, and your inner drive. This starts a good foundation. Your academy training and FTO process make the foundation and structure for the building. If you have ever watched a craftsman build, you know that sometimes they miss a nail or bend it, but, they drive on.
You've probably heard that in woodworking, you measure twice and cut once. This is true of police work as well. You prepare with training and make proper decisions but when you act it will be accurate. Of course, Journeyman carpenters have made errors in their training; so do young officers in the FTO program. Get over it and deal with it.
Failure can be a valuable learning process. Here's a sports analogy. You would never improve as an athlete if you always competed with others who had lesser skills than you. So you win every game, but who is your competition? If you do not compete against those who are better than you, your skills will never be maximized.
This is like the young officer who only wants to do enough to get by or is "good enough for government work." You are not pushing yourself. To get stronger, you must lift heavier weights. That will mean some days you lose and some days you are sore. Police work is no different.
Don't expect to never fail. You will at one time or another. You will be passed over for a promotion or a transfer. You'll make a mistake on the job. It is going to happen. Don't let it keep you from your goals.