As in all things, some people are naturally more gifted than others. We like to call that Talent. One of my Students, whom I had been teaching since she was 10 years old, exhibited that level of expertise. However, there have been many, many times where she needed guidance and advice on technique.
Yvonne Keogh, this man was splendidly talented there's absolutely no doubt. But, he used techniques that can be emulated. I can see that he worked wet-in-wet, added calligraphy and understood his colour mixing and values. Studying the relationship of water to paper and brush to paper, you can begin to replicate some of these images.
I often recommend Ewa Karpinska's book, Wet-on-Wet Watercolour Painting: A Complete Guide to Techniques and Materials, is an excellent resource in learning the stages of wetness. It's ridiculously expensive now, but perhaps you can borrow it from the Library.
Take heart. Even if you are never able to paint in a manner similar to Mirko Hanák, by studying the basic tenets of your craft, you'll improve your painting skills exponentially!