I'm going to expand upon what I was saying earlier.
Suppose you built a time machine, traveled 40 years into the future and saw the condition of your future self. Unhappy with this future self, you decided that you weren't going to have any of it. So, you return to the present and make changes.. only to find, 40 years from now, that you ended up in that same condition.
Fast forward. Now, you are 40 years into the future and you are in the same condition which you saw 40 years earlier. Think about that. You traveled into the future, saw your future self, returned and made changes. The condition you are in, after 40 years of knowing the outcome, was the result of the changes you made trying to avert that outcome. Observing the future influenced your actions and those actions were the cause of the end result.
What would have happened had you returned to the present and done nothing?