"Age" as a topic has always been on my mind. Throughout my life, I have often been confronted with this topic as well as the reactions, conclusions and expectations it has triggered in other people as well as myself.
For example, I have seen the reactions that people show when they ask for my age and then realize that I'm much younger than they would have guessed. This is partly because of my beard and partly because of the way I interact with them. In fact, I have gotten to a point where I let people guess my age because I find joy in surprising them whenever they overestimate it by 1, 2 or 3 years. Ever since, I have been fascinated by this topic and the way how age – a simple number – influences the way how we think about people and how we suddenly make certain assumptions or form expectations.
Over time, I have come to realize that age is really just a number – a number that unfortunately can create more havoc than benefits once it's revealed. I have yet to meet a person who does not automatically and often unintentionally pigeon-hole someone once he/she learns about the other person's age. We often use the age of a person as a metric for comparison. Sadly enough, I often used to do that myself. I would sometimes feel envy when someone was young and successful or try to boost my ego when someone was older and less successful (clearly, "successful" was a subjective metric here). But this practice of comparing yourself to other people is rubbish and a complete waste of your time and energy.
Age is an issue of mind over matter. If you don't mind, it doesn't matter — not Mark Twain
Life is not a competition that you need to win nor should the path of other people influence the path you decide to go down. Don't do the mistake of looking at other people and telling yourself you are more or less successful than them because they are younger or older. Don't compare yourself with others based on a simple number that couldn't be any more meaningless. If you do want to take a metric of comparison, then take your values and ethics, but don't take age and especially not your own definition of success.
On the other hand, don't limit someone's potential just by a number. Just because someone is young, it doesn't mean that the person is not smart, mature, or able to punch above his weight class. And just because someone is old, it doesn't mean the person is not capable of understanding or motivated enough. I would even want to encourage you to make it a principle not ask for someone's age. Unfortunately, this number and the automatic comparison it triggers in our head influences the way how we interact and perceive someone. If you can't turn off this mechanism, at least try not to ask for the age. It's an irrelevant number that can trap your thinking.