For me Genki was the right path, but I understand It can be dry at times. I think what kept me motivated was the though of actually using the new structures in every day sentences and live. Write a little diary of what you did during the day, or on Sunday with what you did during the week.
You can track the evolution of your own language and its pretty amazing going back and watching your language abilities raise from kid like sentences to somewhat elegant.
As for staying focused I guess for me the pure joy of leveling up and developing my own abilities was enough, but when it gets tough create some silly sentences with your new found grammar points. Change up textbook every once in a while with Genki staying as your main.
For me I used Genki 2 and the Manga textbook as I could learn more from Genki but I liked the silly examples in the manga one.
I hope this helped a tiny bit!!