How to actually be 'present' when you're exhausted?

This might sound dumb but I'm genuinely asking. I leave work at 6, pick up kids from daycare by 6:15. We're home by 6:45. I'm absolutely wrecked - mentally drained, hungry, feeling a bit gross from the commute.

Then I'm supposed to be this engaged dad playing with them, doing bath time, reading stories. But I'm just... not there mentally. I'm thinking about emails, or deadlines, or just wanting to zone out.

I love my kids but I also suck at the transition. Anyone figured out a trick that works? Right now I just feel guilty about it most nights.