Something that really aids in the process of forgiving yourself for perceived past 'mistakes' is to direct your conscious energy to identifying and reflecting upon the ways in which you have strengthened yourself and refined your character as a result of having gone through those experiences. That way you can view those aspects of your past in a newfound positive light because you recognize how those experiences ultimately served to help you improve yourself. They served an important function. The more you contemplate this perspective the easier it will be to transmute feelings of guilt & regret into feelings of acceptance and gratitude. : )