I keep a sack of apples on my tack trunk at this time of the year, and dish them up whenever I feel like it. My boy is missing some front teeth and had a hard time biting the apples up, so they either have to be cut (if I remember to bring a knife) or (more often) I hold onto it so he can gnaw chunks out of it. It's messy, but I just rinse off in his water bucket, and then he gets apple-flavored water too. :)
Or, if I feel like watching a show, I toss an apple or two into his watering trough and let him bob for them. I usually take a bite out first myself so that he has an edge to grip.