Hey, 32 years old and got diagnosed with ADHD-Inattentive Type this year.
I guess the big thing is to work with your mental health care team to figure out a treatment plan. Medications for ADHD do work pretty well; I started Adderall and, shortages notwithstanding, I find that it works for me and my body tolerates it pretty well, but your mileage may vary.
Regardless of whether or not you start medication, though, consider therapy or counseling to build better strategies for improving your focus. What I found is that Adderall will help me focus, but not necessarily help me focus on the right thing. Improving your attention span is half the battle, the other half is breaking bad habits and building new ones that help you get things done. For me, my ADHD is coupled with anxiety, so managing my anxiety and building confidence was key.
So yeah, I hope that helps at least a little.