Whatever it is you are concentrating your efforts on, whatever your focus, the best approach is patience, and steady, consistent effort. Skills take time to develop, and the best way to aquire any skill is to practice it every day (or as often as possible) and to focus on one metric only: your rate of progress.
Progress is generally only visible over a period of months and years, it emerges slowly, and tests our patience. We all want to be able to be the best we can be right now, and resent the thought that achieving the level of skill we aspire to might take time, but it does.
A favourite quote of mine comes from Earl Nightingale, and while I'm not a fan of the school of wishful thinking that he is famous for, this quote is useful to anyone who wants to make real practical gains in their lives:
Don't let the fear of the time it will take to accomplish something stand in the way of your doing it. The time will pass anyway; we might just as well put that passing time to the best possible use.
The years wil pass, so we might as well use that time wisely. Looking back on your life, would you rather have completed the whole Call of Duty series, or learnt how to play the piano?
Acquiring skills is one of the most deeply fulfilling things we can achieve as humans, and it is something that is within the reach of each and every one of us. The only thing that stands in our way is our own impatience and lack of discipline. We all suffer from procrastination and distraction. But when you get frustrated with your lack of ability, focus on progress. How much better have you got in the last six months? The last year?
Progress consists of making very small incremental improvements on a daily basis. To achieve this you need to be doing whatever it is you want to be doing every day, even if it's just for 15 minutes. Every minute you can devote to improving is worthwhile, because every minute is an opportunity for progress.
Every minute of frustration, being stuck, stumped, annoyed, or baffled, is an opportunity for progress. Because next time you won't be frustrated since you will have solved the problem, and as long as you keep practising you won't forget. Of course if you neglect your practice then you will forget, for example if you only open Zbrush once every six months then you are likely to be stumped by its UI every time, but if you spend some time in Zbrush every day you will soon be comfortable with it.
Progress is a combination of patience and discipline. Practice regularly and it comes automatically. You don't need to theorise, to compare yourself with others, or to worry about your gift of (or lack of) inborn innate talents, you will always make progress if you practice consistently.
And progress is its own reward, it will encourage you and nurture you if you track it over time. If you you apply yourself to learning a skill, and consistently practice it, you will be able to look back at your progress with immense satisfaction, knowing that a year or two ago you were not able to do the things you can do now.
And the key is to keep making those small, imperceptible improvements, day after day. You will find new and quicker ways to model certain difficult shapes, clever ways to light your scenes, a new and better way of mark-making that adds life and energy to your drawings, or begin to notice the light around you in every day life. And bit by bit you make progress.
It's all too easy to worry about our own apparent lack of talent, or to compare our work against those who are the best in the field and fear that we can never match their results. But those are red herrings, the only person you should ever compare yourself to is yourself. Could the person you were two years ago have created the work you are creating now? Probably not. Is that because you are suddenly more talented now than you were then, or is it because you took the time to practise and improve?
Every minute of practise translates into progress. So be patient, be diligent, and consistently practise, knowing that progress is inevitable.
Another favourite quote of mine comes from the book Art and Fear, by David Bayles and Ted Orland, which illustrates the value of practice and progress over theory and speculation:
The ceramics teacher announced he was dividing his class into two groups. All those on the left side of the studio would be graded solely on the quantity of work they produced, all those on the right graded solely on its quality.
His procedure was simple: on the final day of class he would weigh the work of the “quantity” group: 50 pounds of pots rated an A, 40 pounds a B, and so on. Those being graded on “quality”, however, needed to produce only one pot - albeit a perfect one - to get an A.
Well, come grading time and a curious fact emerged: the works of highest quality were all produced by the group being graded for quantity!
It seems that while the “quantity” group was busily churning out piles of work - and learning from their mistakes - the “quality” group had sat theorizing about perfection, and in the end had little more to show for their efforts than grandiose theories and a pile of dead clay.
So get working, make mistakes, learn, and make slow and steady progress.