how young is to young?

I took my three year old with me deer hunting last year a couple of times although he would have gine every time if I would have let him. We went on one of the coldest days of the year last year and he stuck it out like a champ. The first time we went he wanted to leave and go home but I made him stay and the next time we went he understood that he was going to have to stay. I think one of the biggest things for me as a dad to remember is that the kiddos have a short attention span and so when they get ready to go you either have to entertain them or take them home both of which ruin the hunt, but when I take my boy and now boys (got two now) its their hunt it's about them. So if I can get them distracted by looking through the binocualrs every 30 seconds like my son did last year then thats what I need to do because it keeps them in the woods and keeps them wanting to go back.