Promotion to manager is often dependent on personal performance. Often managers are concerned that those things that they were rewarded for are now things they need to let go. It’s difficult but necessary to let go of the things that made your reputation and to embrace the things that will further your reputation. Delegation, on the other hand, is the important skill of knowing what parts of your job you can, and should, give to others to help them grow and develop. You will find there may be barriers to doing this.