I've got a 20yr. old son I've been trying to 'motivate' to do...anything! Something! I don't care what, just get out of bed before noon and do SOMETHING!!
He's got 30 hrs. of J3 time, starting when he was 6, and recently another 10 in a Cherokee 140. For the small amount of time he has, he does alright, he's trainable, but he hasn't yet opened any of the PPL study books I bought for him. He shows no interest. He never once asks me to take him flying. I always have to drag him out to the airport.
I've told all 4 of my kids, "Find out what you LIKE to do, and then go DO IT", because I don't think you can't force someone down any career path. If they are not into it, they won't be motivated to study or do well, in anything.
My son is just not into anything right now, except surfing. He's at the local community college, living at home, but still has no idea what he wants to do for the rest of his life. I think he just wants to live and home and have his mommy take care of him, which she is only too happy to do.
I wanted to be an Aero Engineer and design airplanes, until my freshman year of college, when I found out sitting in a cubicle disigning nuts and bolts for brake systems was going to be my future, if I was lucky.
It was then that I got serious about becoming a pilot. Seemed a lot easier than digging ditches, and more fun than sitting behind a desk in a room with no windows.
But I think you really have to love this flying stuff, if you are going to stick it out for a full career. Lots of people say, "I've always wanted to learn to fly!" But how many of them are willing to sacrafice the time and money necessary to make it happen?