2 Corinthians 7:10 For Godly sorrow worketh repentence to salvation not to be repented of: but the sorrow of the world worketh death.
Regret is ruining the lives of countless people by stealing their joy. Certainly you have things you wish you had done differently. But there is no sense becoming burdened with regret over something you have no power to change. You need to understand this is the way the devil works. God will warn you so you can change your mind before you make a mistake. Satan waits until it is too late, when you can no longer do anything about it, and then tries to heap regret and condemnation upon you.
Don't allow Satan to steal from you any longer. Ask God for forgiveness, if you haven't already and leave your regrets in the past.