Just when we are sure it is dead, it turns up somewhere as robust as ever to trouble our peace and poison the fruit of our lives. Our capacity to say no, is one of the most impressive features of our language. The ability to say no gives us enormous freedom. Only humans can say no. Animals can't say no.
Animals do whatever their instinct dictates.
Saying no protects us from danger and ruin and heartache. The ability to deny ourselves sets us free to follow Jesus. Following Jesus means carrying your cross. It is a lot easier to live a totally devoted life than a partially devoted life. It's easier to carry the whole cross than half a cross.