From That's Funny, You Don't Look Buddhist, by Sylvia Boorstein 

My grandmother was entirely solicitous of all my physical needs. She cooked things I liked. We took walks together. She bathed and dressed me and braided my hair. She sat by my bedside and sang to me until I fell asleep. And she was sensibly philosophical about my moods. Sadness didn't worry her. On those occasions - which must have been frequent enough for me to remember - when I said, "But I'm not happy!" she would say, "Where is it written that you are supposed to be happy all the time?" She must have said it kindly, because I don't remember it as a rebuke, and I think of it now as my introduction to the first of the Four Noble Truths of the Buddha. Life is difficult. Just because it is. Because things change. Because change means loss and disappointment. Because bodies and relationships are, from time to time, painful. I was reassured by my grandmother's response. I didn't feel I was making a mistake by feeling sad, and she didn't feel obliged to fix me.