Most people will experience some discomfort especially at first. The level of distress will differ depending on the type of braces that are installed. Younger patients seem to have less trouble adjusting.
Your lips may become more sensitive as your mouth becomes accustomed to the braces. You may experience some pain when the braces are first installed and again when they need to be adjusted.
Your dentist will discuss the process with you so that you will know what to expect and how to deal with any problems. Let him know if you experience any severe pain.
Your dentist may recommend using dental wax to prevent lip sores and a mild medication for pain. You will need to stick to a diet of soft foods for awhile. Other than that just give yourself time to get used to your braces.