First time traveler needs help.?

I have never been on a plane nor have I ever traveled to any place far, or that has a significant climate change. I'm wondering if I should can take any vitamins or anything to prepare me for travel so I don't get sick. People have been telling me to boost my vitamin intake because I'm going from kind of chilly (Toronto in the fall) to hot (Florida). And the climate change may make me sick. what sort of vitamins could I be taking that could help my body?