"You need to persevere so that when you have done the will of God, you will receive what He has promised"
You cannot persevere and look back at the same time. The past should only exist as a lesson of what not to do again, not as a means of not moving forward. Remember, your promise is in front of you, so just keep on moving. Everything that has already happened, God has already brought you out of it, so keep on pushing and moving forward towards His promise.