I should mention meta skills, skills that are more general:
1. Learning to learn. When you learn to play an instrument or a language you should learn to learn better. So learning something new becomes easier.
That is learning about space repetition software and how your memory works. Physical and mental fatigue,moderate stress, diet, relaxation times and sleep.
One of the best abilities that you could master is the ability to learn from the masters in any discipline, what is called in psychology "modeling", and it is natural for kids. That usually takes letting some part of yourself to die, accepting that you are wrong at something, and it for adults is incredible painful and rewarding at the same time.
2. Managing your emotions in front of your opposite sex, in front of threats, in front of a big audience. In front of important work to do.
Getting gradually out of your comfort zone. Taking and handling bigger and bigger risks while knowing your limitations. Again that means accepting (a small)suffering as a routine.
Being conscious about what you are feeling at every moment and knowing what to do helps you master procrastination in you and in others.
That makes you incredible attractive and resourceful person.
To speak in front of lots of people you need to have something important to say to them. You need to find something more important than yourself.
In general those skills are counterintuitive, like doing routine exercise means suffering a little every day but over months or years it improves you so much most people just wont be able to compete with you at psychical or metal tasks.