Imagine you were born in a field, and lived your entire life outdoors in this same field. Now imagine that on your 20th birthday, you discover a fantastic space ship that can travel well beyond the speed of light. If you get in this ship, and travel away from Earth at several times the speed of light, you will eventually find yourself at a point where you could look back and see the light that was reflected off the Earth at the time of your birth.
Now imagine that this ship also comes equipped with a super powerful telescope, one so powerful that you can point it back at earth, and zoom in to that field where you were born. With this telescope you observe yourself living out your life.
If this scenario took place, it would mean that for the first 20 years of your life, some future version of yourself was watching, well aware of what you were going to do before you did it. Would that mean everything you did was unavoidable?