"He thinks that practicing a couple of times a week, and a couple of lessons a week are enough. I know it takes more, but he does not understand that, since football comes so easy to him, and he is very good at it with little preparation."
Let life teach him. Practicing everyday is standard. Where we are, to make the field, you are practicing everyday, plus working out on your own or with a trainer on the side. Life shows you what it takes, and it appears it is. It doesn't sound like he loves it. If he did, sitting last year would have burned enough to practice more. It know you want it for him, like we all do, but if they don't want it, it is usually taken away.