Answer:
If you lose me you may cause people around you to lose me too.
I don't live within a house nor do I live without. Most will use me when they come in and again when they go out.
Mr. and Mrs. Mustard have five daughters and each daughter has one brother. How many people are there in the Mustard family?
I can swim but never get wet. I can run but never get tired. I follow you everywhere but never say a word. What am I?
Find me on body builders or in the drink aisle.
Give it food and it will live, give it water and it will die.