Practice, right? Yes. However, it's how you practice. Repetition is how you do it. Unrelenting repetition. Whatever it is that you are trying to improve, keep practicing it, over and over again. It must become second nature. The only way to reach that advanced state of execution is to practice it repeatedly.
Usually, you would do this on your own. Don't expect anyone to put the time in with you. Do it yourself. Know what it is that you want to practice and do it.
If it is "repetitious" and "boring" to you, then you probably won't be able to stick with it and won't get anywhere.
However, if the "repetitions" are exciting and invigorating to you, then it's working and you are on your way to improvement!