I have to agree with Ken. Hard work is very important. But it can only take you so far if you do not have the proper genetics. Alternatively, just having the proper genetics won't guarantee you success without also putting in the hard work.
For example, we all know that Barry Bonds used PEDs to increase his size and strength. But, studies also show that his eyes and brain see and process information faster than average, which allows him to respond to a 95 mph fastball, swing the bat and make a hit. Without that key advantage, it's doubtful he would have been as successful as he was, even with hardwork and PEDs. (As a reminder, his father was a pro baseball player too.)