As a forty-something year old, I've also been struggling with digital overload and have spent this year working on it. One of the biggest things is reducing emails. I've created a new email account and started migrating anything I want to keep using over to that address, and whenever I get an email from a mailing list, I immediately unsubscribe. I remove email notifications from any service I'm still using but don't want to bug me, and I close any account I don't want anymore. I've gone from around 200 emails a day to less than 10, and most of those are for a job search which will be unsubscribed from as soon as I'm employed again.
A lot of work to get this far, but so worth it.