I don't have answers. I do know it has to come from the person.
My son and daughter both see the effort I put into tennis (and music, my other hobby, not to mention my job that actually earns money). Whether it's hitting against the wall to fix a stroke problem, or running a scale over and over, they see the benefit of practice. But ultimately they have to decide if they want to put in that effort, and what things are important enough to them to make that effort. I'm not a believer that you need to be the best you can be at every single thing you do, but I do think there should be some things in your life that you are willing to work for and be your best at.
You try to be a roll model. you try to help your kids, but they have to decide. Do let them know that they are loved unconditionally.