How can I master this art of life?

When I have an argument with my husband or when I'm feeling down I cant help but look miserable. I find it surprising that some woman are able to stay or even just look happy despite some problems in their marriage or life in general. Whats the secret to being happy or at least looking happy? I'd rather look happy even if I'm not coz I think looking unhappy affects people around me negatively and also it broadcasts to everyone that something is not right in my life (washing dirty linen in public). On most of my photos you can see just how unhappy, stressed or miserable I look. I think my problems are ordinary but I am lacking the emotional intelligence to handle my hurts, pains and disappointments well. How can I look bright and happy most of the times? Any emotional intelligence tips or anything else?