How to actually be PRESENT after 8 hours of work

I pick up my kids at 5:45pm. They want my attention immediately. I'm exhausted. Brain is fried. All I want to do is zone out with my phone but they're asking me to play with them, build Legos, whatever. I feel like I'm failing because I can't muster the energy to be genuinely engaged. I'll sit there playing but half-present and I know they can tell. How do people actually transition from work mode? Is it just practice?