Okay, so maybe they are a little immature, but as I said before, the years went by so slowly. Every day was a new adventure. Now that I'm bigger, the days go by almost without number. Time passes more quickly for larger beings. Maybe this explains why it's so hard to swat a fly.
Time seems slower to flies, so they have a longer time-span in which to react.
Sure, my dad swings that paper as quickly as he can, but the fly, especially a little one, will see it coming with plenty of time to get out of the way. Of course, there is a perfectly logical, biological explanation, but it does go along with the idea that, as a traveler's speed approaches the speed of light, time will come to a halt and his mass will decrease to nothing. To tell you the truth, it beats me. It's just a suggestion. Maybe if we can shrink ourselves down to the size of a fly, we'll have more time to live.