You can be serious about your future and still be ridiculous at lunch.

Seriousness about where you are heading gets confused with seriousness as a personality, and they are not the same thing. Your direction is set by a handful of decisions. The rest of the day is still yours, which means you can be planning hard and also be the person who makes everyone laugh until somebody chokes on a drink.

Notice whether you have started performing maturity in places where nobody is grading you. Keep one part of your week deliberately unserious, and protect it the way you protect study time.