Focus means letting some interesting things remain interesting somewhere else.

There is more that is genuinely worth your interest than you could ever pursue, and that abundance is exactly what makes focus difficult. Letting something remain interesting somewhere else, without you, is not a rejection of it. It is an acknowledgment that you are finite.

Keep a list of things you find compelling but are not pursuing, so they have somewhere to go other than your working hours. Revisit it occasionally. Naming them as deliberately deferred is easier than pretending they do not appeal to you.