Talent is from G-d

 Derashos HaRan (#10): The Jews were first commanded concerning two things. 1) Not to view their success as resulting from their own strength and abilities. 2) Not to view their conquest of Israel as being the result of their merit... While it is true that people vary in their talents and abilities, e.g., some are more intelligent than others while others are more skilled at making money than others. Therefore the rich man might say that he succeeded because of his inherent abilities. In order to forestall this conclusion, G d therefore said that it is important to remember that He is the source of this ability... One cannot deny that talent is critical to achieve success but one must never forget that talent is G d given.

Abarbanel (Devarim 8:1): Moshe did not want to reject the necessity of competence for success but provide the context for understanding its importance. Therefore he said: Remember He is the one who gave you strength to succeed. After all how can one deny the role of strength in farming and caring for cattle and property. These means to success cannot be denied since they are so self-evident. However the truth is that a person is the cause of his success but is the intermediary cause not the initial cause. It is critical that a person realize that while his efforts and talents are needed for success but G d is the provider of the conditions for success. 

Ramban (Devarim 8:18): But you should remember G d for it is He who gives you the power to succeed… It is well known that the Jews are powerful heroic soldiers in battle as we see they are compared to lions and wolves. Nevertheless they were defeated in battle by the kings of Canaan. Therefore the Torah tells us that if you think that your strength and own efforts are the sole basis for success - you should remember the redemption from Egypt. At that time you had no strength or capabilities at all. Furthermore you should remember in the desolate desert where there is no chance of natural survival - G d provided all your needs. Consequently you should understand from these facts - that even when you when you have strength - it is in fact G d who is provided this strength. If you forget this then G d will remove your strength and you will be defeated as other have. That is because whoever deserts G d is obliterated…