Hence, I am looking for ways not to spread myself too thin all over the multitude of stuff I wish to be able to do and master.

Concentration on only a couple will likely lead to fast improvement and more motivation during that time, before moving on. They say "choose the ten things you want to learn, and then cut 7 of them."

That said, I think that this struggling could be dealt with by just training my focus a little more.

Perhaps the cause for it is because you have avoided it in the past?