How can a person at the age of 18 be more mature?

so me and my bf have recently talked of the subject of maturity and it just so happens he told me that i need to do some growing up. im going to college in a month and a half, im about to get 2 jobs, im helping my dad run the house all while trying to maintain a social life. i know im 18 and i know i still ahve some growing up to do, its obvious to me. so how can i be more mature when i already know i need to be?