"Do not let what you cannot do interfere with what you can do".
If you were to know everything, you would not need to learn anymore. It is not as if it is impossible to know everything in the world but that will not be realistic because there is hardly ever enough time to learn and acquire all the skills in the world, not even in your own niche. Your brain has the capacity to take as much information but the major problem is you would need more than a thousand years to fully learn all that.
It may seem vague to you yet but there are countless people who have just given up on themselves and their capacity to impact the world because they see their limitations too much.
This is similar to my previous post on how making attempts makes people become champions.
Every attempt gave a different variant of the word, like "boak", "baok", "boek", "bokk", and so on. Why was it so difficult to get the wrongly spelt letter in the word?
Some would say, "he is poor because he has no formal education". Sound reasoning, hm? But when did formal education only, become the determinant for your self-fulfilment?
It would be a different thing, when you finally acquired your degrees, probably poor because he is handicapped on one finger.
There are many physical limitations that many people have capitalized upon to remain static all through life, whereas, those who have learnt to see beyond those limits are making exploits still.
As far as life is concerned, what you need to succeed and stay satisfied is already within you.
In as much as you try to meet up to varying standards dictated people and firms and organizations about what you can do or cannot do, you must never get caught up in the web of accepting that you achieve much because you keep spelling "book" incorrectly.
And in John Wooden's words, do not let what you cannot do interfere with what you can do and achieve. Therefore, you must know that you are beyond what you cannot do. There is time to learn as much as you can but if you ever think you can know everything before you succeed, then you are planning to never be successful.
In other words, you do not have to be a professional, a doctor, a lawyer, or the likes before you achieve your dream