I have a few acquaintances who were diagnosed in their 20s and both seem to be doing as well as they can be after 20+ years.
I know it's early, and he's still waiting for results, but one thing that helped them significantly was improving their diet and increasing their physical activity. Depression or hopelessness could get the better of them, but in-activity could make things progress more quickly.
https://mshope.com is run by Calgarian, Matt Embry and is a good resource for early diagnoses. Something that can go hand-in-hand with what their doctors suggest.