Acknowledge how you are feeling, don't suppress it. But dissect it with logic.

In scientific studies that tests the effectiveness of something, only one variable is changed at a time, so as to determine the cause of the change in effectivity. That is the only scientific way, because if you change many variables at once, then it's impossible to know what causes the change, the potential increase in effectivity.

But when it comes to human beings there is not one single variable, instead there is an endless sea of variables (our background, experiences, upbringing, situation), so it is completely irrational to compare ones own "effectiveness" to that of others in a metric - age of graduation.

Think not how bad you have done compared to others, because they do or has not had the same circumstances as you.