Well, not all the time anyway.
Happiness is not so much a state of mind as a continuum. Obviously there are people that are more happy, generally, than other people. On the other end of the spectrum there is the very real issue of depression. I am not a doctor and have never been a mental health patient. But I know how this works.
I try to not let myself get too high these days as I know that I tend to bottom out after being "too happy". Much like doing a drug that floods you with dopamine I often crash into that coming down state on nothing more than emotion. The results can often be worse since coming down from a drug usually has a prescribed time period.
Not letting myself get too high does not mean that I am not happy. I am. Sometimes...
Some people that are diagnosed depressed will get angry if you mention exercise. All I know is what works for me. If I get regular physical exertion and eat right I am better physically and mentally. To me it just makes sense that a good diet and regular exercise would help your overall health.
Again, your mileage may vary, but for me another key is being prepared for happiness. What I mean by this is that you have to be in the right frame of mine when good things happen to fully appreciate and enjoy them. You can ruin even the coolest experience if you are determined to do so.
So if things aren't great hang in there, start eating better, and get on your feet and sweat. If things are good appreciate it, it won't last :)
gud post