Struggling to engage in play

I am a FTM with a 13mo. Motherhood is everything I hoped it be, but I struggle to stay focused and engaged when my baby wants me to read the same book several times in a row or wants me to stack the cups so he can knock them down over and over. I know these desires are developmentally appropriate and I love him so much and I want to play with him and treasure it, but I struggle to stay engaged. I'm one of those people who is always doing two things at once unless I'm meditating. Any advice?