Early in sobriety, my sponsor had me do a to do list everyday. I wasn't working at that time. A big part of my to-do list was 15-20 minutes three times a day "playing" with my toddler. It helped to relieve guilt of feeling like I wasn't doing enough as a mom while the crazies were rampant.
Just force yourself 15-20 minutes of trying to play. Even if he doesn't seem responsive. The same times each day, will train both of you that's it playtime with mommy.