Recognize that different people have different personality styles and communication skills. They may sincerely mean to help, but deliver negative comments in a way that is hard to process and accept. On the other hand, an ill-wisher often provides valuable insights. Decide that it is never productive to take any comments personally. Seek out criticism.
Some jobs offer regular job performance evaluations where employees get feedback.
If you don't have such a program, ask for personal feedback anyway, from both your manager and those you manage. Recruit your customers as allies by asking them to be your critics. Don't be defensive. Keep your clients happy by being as eager to please them as your competitors are. In any selling situation, you're still selling after the sale.