In an imperfect world where unforeseen occurrences happen and things beyond our control affect us, happy ALL the time is not even a practical request of life. However, contentment all the time is, and happy most of the time is definitely attainable. The answer comes from the best source available.
v3. Happy are those conscious of their spiritual need, since the kingdom of the heavens belongs to them.
v4. Happy are those who mourn, since they will be comforted.
v.5 Happy are the mild tempered ones, since they will inherit the earth
v6. Happy are those hungering and thirsting for righteousness, since they will be filled.
v7. Happy are the merciful, since they will be shown mercy.
v8. Happy are the pure in heart, since they will see God
v9. Happy are the peaceable, since they will be called sons of God
v 10 Happy are those who have been persecuted for righteousness sake, since the kingdom of the heavens belong to them.
v11. Happy are you when people reproach you and persecute you and lyingly say ever sort of wicked thing against you for my sake.
Yes, you guessed it, the answer is found in the bible and these verses at Matthew 5:3-11. (New World Translation)
Both contentment and happiness began with a person internally. What you put out is what is returned to you. When you put out positive energy, smile at people and look them in the eye when speaking to them, when you listen to people, when you help others and put their needs before your own, when you are kind to those needing kindness, all these things will be returned to you. Now not necessarily from the same source to which you gave but it will return. You also will feel the rewards that come with showing LOVE and giving.
That is where true happiness comes from. It is not in material possessions. It is not in the company of any one person. It does not come from financial success or popularity.
Just give it a try and you will find contentment, and happiness will always be in its shadow.
I hope that helps.