In general, the public has a poor understanding of being a professional athlete. Typically, when I try to explain it to others, I usually just say "it's a job like any other" - the same as staying on top of your game in the music industry, running a startup, etc.
It's easy for us to dismiss the effort professional athletes put out when you only see them on TV a few times. However, it's somehow different when we see Steve Jobs or Tim Cook on stage a couple times each year. We recognize all of the hard work Steve/Tim likely put in behind the scenes.
For some reason, a lot of people don't recognize that same level of effort for professional athletes. They just assume they show up for the game and perform at a high level.
For every hour on the field, there's probably two hours of study (mental preparation) and two hours of treatment and/or rehab (physical maintenance). Pair that with a rigid schedule every day, fatigue is a real concern.
We all know the overnight success myth. The myth exists for professional athletes as well. Athletes that make it to the highest level didn't simply wake up one morning and have all the tools to succeed. Hours and hours and hours of training, both mental and physical, had to occur. It's like anything else - you don't simply get good. It takes practice.
It also takes commitment, dedication, and perseverance to succeed at a professional level - just like everything else in this world.