 You might be just like me, so check it out. PlanZDiet.com. Life jackets aren't only for kids. If you fall out of the boat, you can get into trouble, no matter how good a swimmer you are. I learned about cold water shock in my swim class. When your head goes underwater, your mouth opens and you gasp for air. If you're not wearing your life jacket, you'll drown. Hey, you are pretty smart. So are you going to wear your life jacket, Grandpa? Check.