All grannied out

[Whingey]

Went out to dinner with 2 grandchildren and parents and exhausted. How can I get energy level up?

I know the feeling, OP.
I can recommend feet up on the sofa with a good book or TV - and then falling asleep.🙂

Put on music/audiobook/podcast and sit down for a bit in a sunny spot if you have one.

Also, revel in the fact that you can say good riddance to the little dears at the end of the afternoon without having to wait around for bedtime - I'm jealous