Shalom Brother,
Great to hear that you are good and feeling good.
Finding koach in a new, healthy outlet sounds like a great idea. What interests you?
As far as checking WhatsApp (or anything else an excessive number of times - like the news), it's a good first step that you are aware of the distraction and how it is affecting you. Maybe you can turn your phone off, leave it in your car or out of reach, give it to a friend, temporarily turn off the data (does WhatsApp need data?), use parental controls to block the app for 30 minutes at a go. You could also ask a closer friend to gently nudge you if they see you taking out your phone too much and remind you to put it away.
I can relate to struggling with this. It helped me tremendously to mute all statuses. If it dings, I have a message - otherwise nothing is happening. I also left some "chattier" groups that were not essential.
Hatzlacha and Kol Tov