OK, say you wanted to go back in time to, oh, say you had to influence your toddler self to do something. In reality, if did go back in time, you would remember a strange future version of yourself coming to visit you, and so you would have probably done what he wanted and influenced yourself, thereby making yourself what you are, and nothing would have been changed. So, the cycle continues through countless timelines:

• You see a strange future version of yourself when you're a toddler
• You influence yourself according to his instructions
• Years later, you go back in time to influence your past toddler self
• He grows up, goes back in time, and the cycle repeats endlessly.