I'm carded for R-rated movies. And I get talked down to a lot. When I try to go rent a car or buy an airplane ticket or other stuff adults do I get 'Okaaaaaay honey.' I remember when I was 18 getting crayons in a restaurant.
If you always put limit on everything you do physical or anything else. It will spread into your work and into your life. There are no limits. There are only plateaus and you must not stay there you must go beyond them.