Well my advice for people who have a hard time interpreting body language is when your trying to figure out whether someone you know is sad, bored, happy, or mad all you have to do is observe what they do or how they react to other people. For example, someone that is mad or angry at the moment would react a bit rudely around others and might give a cold stare. Or someone that is happy would be more outgoing or more brightening or anything that has to do with being happy. However, if you can't tell how the person is feeling then try to talk to them and get them to be honest and let out the emotion that they feel. If they are feeling any negative emotion like sadness or angriness try and cheer them up, like make a silly face or tell them something nice or even take them out on a shopping spring! :D (unless you're broke like me lol then you can do something else).