My advice would be to keep up with a schedule that still keeps you pretty busy and ideally waking up early at regular hours. Once you hit actual rock bottom burn out, you know sleeping in until noon and scrolling message boards for three hours before you realized you haven't eaten yet all day and the sun is already setting, it feels almost impossible to turn the switch back on when you need to. Even something like folding your clothes starts to feel like a monumental task pretty fast.
As a widower who just sent his kid off to the grandparents to visit for a few days, and is now missing his person, his kid, who relies on him and feeling the effects of missing purpose...
Sure, it could be kids, a partner, a spouse, or a friend or family. But it could also be the rest of the team on the weekly bowling league, the puppies at the shelter who need playtime each week with a volunteer human, the community one serves as a volunteer firefighter, the homeless shelter where one helps serve the weekly dinner, the neighbor who needs help with yard upkeep, or any other parts of the village where one lives that relies on you, and makes you feel included, involved, and fulfilled inside by having that purpose.
Not sure if you're single, but go on some dates. Getting excited about another human being can be a huge boost. You don't need to replace work with other intellectualism (though you certainly can!)
