a merry heart does good like a medicine,what does this mean?give us an example

a merry heart does good like a medicine,what does this mean?give us an example “A merry heart does good like a medicine” What does this mean?Give us an example.最好具体解释 May your Christmas be merry as a song And your heart be happy the whole year long!May your Christmas be merry as a song And your heart be happy the whole year long! merry merry merry merry merry My heart tell me my dear friend.merry christmas a very merry unbirthday是什么意思 帮忙翻译歌词Have Yourself A Merry Little ChristmasOh yeah, mmm Have yourself a merry little Christmas Let your heart be light From now on your troubles will be out of sight, yeah Have yourself a merry little Christmas Make the Yuletide gay From a heart to heart that the heart does go ''Heart does not move,not pain.If a moving heart,tears on the 1000 line ''翻译成中文 Being strong does't mean having a stony heart.but having a smile through the tears 【we wish you a merry christmas】中文 Merry Christmas and a happy newyear Merry Christmas and a happy newye