Everyone wants to be happy in his life; it reveals nobody can achieve happiness in his life, as not all the continuants of happiness can be achieved simultaneously at any time in his life, i.e. satisfied job, handsome salary, good health, positivity, love, purpose, selflessness, sense of choice or intelligence, is it not?

These are all mental perceptions of individual writers, not a scientifically proved truth. Obviously, all these things cannot be achieved at a time by almost all the people. You have not named the author and his contact number. I would definitely have asked him, if he is having all these things and is really happy. So, if you know the author, would you like to ask him to prove, if he has any such example of any person in the world, who possesses all these elements?

Not everyone is supposed to enjoy good health all the times. Not everyone can remain positive all the times in his life. Negativity of a person depends upon the circumstances and attitudes of others towards him. Not all the times, a person enjoys love or can shun hatred due to one or the other reason. Not all the times, a person has the purpose of doing things, as he can be compelled to do a thing quite unwillingly and without any of his purpose being served, like that happens in the life of workers/ executives in employment. In majority of cases a person does things with selfish motive only, not taking care of how that can prove to be harmful to someone else. There is a great difference between sense of choice and intelligence. Choice depends upon emotion, passion & sentiments of individuals. These human elements have nothing to do with his intelligence. Where intelligence is used, element of choice gets restricted, as intelligence can work against personal choices of a person, as choice of a person depends upon individual's taste, liking and even compulsions.

Mostly nowhere his brains play part in choice. Suppose you chosen to do a job in company 'A'. You make hard work to find job with that company, but you fail with the reason, either there is no vacancy in that company, or your candidature is rejected, or you are not able to apply for the post in time, being not able to know when vacancy declared.. So, where remains the question of choice for you. Now since you are not sure where you will be able to get selected, you apply in ten different companies and you have to be satisfied with a job in company 'Z' when that was your last choice as the work culture does not suit you, being not able to get accommodated in other 9 companies. In that case, where the sense of choice works.

In the same way, assume due to your sharp quotient, you have come out with amazing achievement in your interview of a company, but at the last minute, the management is compelled to accommodate some other person recommended by some political bigwig. So, where any one's intelligence is relevant to his sense of choice?

So, pleasure frequently fades away with the unfriendly homely environments and woring conditions of the place of work of a person and to some extent due to other outer world's influences.

 As I know a very simple method "Not be unhappy with your lot, become the master of your own fate, vie for regular progress of your career in a phased style according to your own capacity and capability by bravely facing all the odds of your life with full confidence."