I love having bad days (yes I do have them, just like everyone else in this world.) Bad days remind us of a very important thing: not everything in life can be perfect, but most important, you are still alive. I do not mean the literal meaning of alive (breathing, pulse etc...). I mean that you are still able to get angry. You are still able to become sad. Things upset you. Now you can choose to let the things that upset you ruin your day(sometimes I let it happen out of spite), or you can acknowledge that it happened and move on.
That is where the happy part comes in. Since you are able to recognize that you are having a bad day, now you should be able to congratulate yourself for getting through it, and be proud of yourself for doing such a GREAT JOB! We all get angry, we just need to know how to control our anger, sadness or whatever negative thoughts we have, and think of and do something positive to counteract the effect.
Happiness comes from all sorts of places; you need to open your eyes and just see.
:o) I had a bad day today, but I made it through alright