You're describing a prioritization problem, not a focus one. Prioritize the items in your life and then put the proper focus on them. Also, and this is a big one now, actually focus on those items. When you're cultivating a relationship with someone else, don't have your focus on your phone or work. This ties into the common phrase about being present.

Also, for me it was more important to understand what NOT to focus on. Figuring out that which truly does not matter and letting it go is one of the most freeing things I have done. It's also a skill/tactic I see at all levels of life. The big picture of your whole life, then there is your work life, then there are work problems, then in jiu jitsu, etc... And the funny part is that people know bike-shedding exists and still do it day after day.