Nobody feels old at 16 until they meet a 12-year-old. Age is a comparison, not a number.

Age is experienced as a position relative to whoever is nearby. On your own you are just yourself; next to someone four years younger you suddenly feel ancient and competent, and next to someone four years older you are a child again, all within the same afternoon. The number did not move. What moved was the comparison you happened to be standing in.

When you feel too young for something, notice who you are measuring against and whether that person is the right ruler. Usually they are further along in one specific thing, not in general. Ask them how long it took, which tends to shorten the distance considerably.