Why can't we force our emotions when we are truly happy?

Being unable to control emotions can be temporary. It could be caused by something like a drop in blood sugar or exhaustion from lack of sleep. However, some people experience a constant inability to control their emotions because of a chronic condition.

Emotions come from within and how we feel, also how we interact with those around us.

Example:

If you are alone in a dark room you will most likely be scared, or if you are in a bright colored room with people you like you will most likely be happy or neutral.