One of the benefits of being alive today is access to information that your predecessors could only dream about. The great archives and libraries of yesteryear's Science Fiction are here and now, and better-connected than ever before. That means that answers to questions are easy to find, and once found easy to disseminate.
This past Saturday we had a brilliant post about portraying master martial artists. You need not take Cheah's word for it; go to YouTube, or Vidme, or Dailymotion (etc.) and look for videos of martial artists in action. You want to watch real and unreal ones (i.e. live-action fight choreography) doing their thing. You watch the real ones because you want to watch what can actually be done with skill, practice, and determination to Git Gud. You want to watch the fight choreographers to see how they tell the story with action, mating beats in the story with turns in the fight. (Compare with Howard and Burroughs. They got it.)
Yes, as writers you're working with words and not video or audio, but action and adventure has its roots in the written word. Generations of writers before you thrilled readers with their vivid depictions of swordplay, sails flush with wind, salty air filling one's nostrils, native girls inviting traveling men to warm beds with but a look, the cackling of a contemptuous angel in the shadows just before delivering judgement with volleys of copper-jacketed lead slugs, and the clippty-clop of iron-shod hooves on ancient city streets covered in ceramic tiles.
You saw those swords, didn't you? You heard the wind fill those sails, didn't you? So don't feel ill at-ease watching others do such things as execute a complex takedown, demonstrate the tactical reload for one's service pistol (You did see John Wick, right? Shown there.), or how to execute car stunts that you'd swear were only in the movies. Your vocabulary is paramount as a writer, so embrace every new word you encounter and love it as a priceless treasure from a lost antediluvian civilization.
Your stories will benefit from your judicious use of a broad and deep vocabulary. Your master marksman will talk of ballistics, doping his scope, twist rate, bullet weight, felt recoil, and other terms that you--who may not be as familiar with what goes into being a master shooter--may not know. You don't have to be one yourself, but you should know what goes on in the mind of such a man- and the words they use are good indicators of their mindset.
Top-tier fighter pilots, veteran race car drivers, all-conquering warlords, successful spymasters- it's not just in writing martial artists where having a clue about what goes on will benefit greatly in portraying them properly and successfully. Putting all of that to words, and picking the right words to convey the desired image to the reader, is the specific skillset that you will develop as a writer. We're called "wordsmiths" for a reason, and writing is called a craft for a reason; this is it- learning how to take all sorts of material, then heating and hammering that material into the shape of a story that entertains your intended audience.
And the best part? You get to have fun while doing it, from start to finish. Why else are we such a joyful lot? Come on, friend, and fear not; even when you're rejected, you still have a good time. So get to writin'!