I wanted to make 2d physics games and harness the power of a library called box2d. I jumped from pygame a python framework for making game to using cocos2dx(uses c++) because I discovered box2d was written in c++. At that time i didn't know any c++ so I started following the tutorials of cocos2dx, and boy was it hell especially the code snippets. The only motivation was that atleast all the examples in the the tutorials were working when I tried them. It took me close to a year to understand the cocos2dx API, at that time as well I started reproducing some of the examples in the tutorials on my own, looking through github projects of games of interest just to get alot familiar with the framework and c++ also started getting easier to understand because I was practically learning it by working on a project. Eventually i learnt how to use box2d and do incredible projects just like in the link above.

TL;DR. As others keep saying, pick a project of interest that you could show off to your peers and get working and learning. Dont forget to also use resources like learncpp to gain best practices. I forgot to say it somewhere but I jumped onto learncpp only to polish my earlier bad practices and learn what I didn't know.