In a few days, I will be 77 and I have learned a thing or two about how to achieve happiness.
a) First, it is a scientific fact that it is impossible to bring happiness to others without bringing twice the happiness to yourself. Incidentally, I have also verified this by personal experience. So, whenever you get a chance, bring happiness to others and you will bring happiness to yourself.
b) Secondly, risk bringing a smile or even a laugh to others. In the modern civilization, this has become risky in that people might think you strange. Nonetheless, when you make someone else smile, or even laugh, you will find it difficult to avoid doing the same. Caution: bear in mind that some people will resist being happy at any cost and might actually scowl.
c) Be grateful and be quick to show your appreciation.
d) Be quick with compliments. This one can get you in trouble in this modern world. Some people might take this one the wrong way. I have had this happen to me many times. I have found the indirect approach far safer. Complement them on a vehicle. For me, that has always worked.
e) Finally, and most important. There is no way a person can truly be happy unless he is right with God. It is really where it all starts. Accept Jesus as your Lord and savior and the above becomes more natural. The happiness becomes greater and more permanent. It is the way it works because it is the way He designed us.