Exhausted with entertaining grandchild

Do you ever get bored or exhausted when entertaining grandchildren? I feel guilty because although I love my 3 year old grandson very dearly, I can only play chou chou train for so long.
We babysit about once a month and he stays over for a night or two so 2 to 3 full days. By day 2, I am exhausted and embarrassed to admit but can’t wait for his parents to pick him up ! Always having to find ways to entertain him and playing with balls and trucks and trains and talking constantly. Trying to read him a book or sitting down with crayons is near impossible because he is very active and needs to move non stop. My husband will take him out for a walk to give me a break while I cook and pick up a bit but he is just as exhausted and I am. Also we are not used to waking up at 5am. At 5:15am we are up and playing.
How do you grandparents do it? Do you truly enjoy it?
My friends who are grandparents can’t wait to have their grandkids over and just love every single minute with them. What’s wrong with me (us)?