Pay close attention to the words and thoughts you use throughout the day.
Words like "I can't" or "I don't" (play well, memorize, learn fast, count well, get a good sound etc. etc.) will shut down your mind's ability to find answers. It will simply agree with you and prove you to be right time and time again.
Questions like "How can I?" or "What do I need to do?" (to play well, memorize, learn fast, count well, get a good sound etc. etc.) will open your mind to the solutions. Your subconscious will work on the problem for you and you will get the answers much more rapidly.
Remove "I can't" from your vocabulary - replace it with "How can I?"