It really does come down to playing more at the end of the day, but there is more to it.
When I started 7k, I was already pretty good at 4k and didn't have the same motivation for 7k. However, just start out slowly and watch the improvement. The first week was a struggle as I tried to play with other fingers. After that, it was doing that but faster.
Also, the best motivator is improvement. That's a good thing too, because improvement is very common in the early stages. After a while of that, you'll find it more fun and enjoy challenging yourself more and more. You'll play the maps that you want to play. Nowadays, I find myself playing more 7k than 4k tbh.
All in all, do 7k if you want to do 7k, and have fun.