A shift from Short term to long term and vice-versa

I know some people whose main purpose in life is to "stay happy, no matter what".

One of such persons has the following to say: When you feel sad about something short term that has happened, try to forcibly divert attentions to long term things which would give you happiness. That way you would be able to divert attention from the bad feeling you have due the short term aweful thing that has happened. And you would do the otherwise, when you have some sad thing happened because of a long term thing. Just divert your attention to short term happiness. Khatam aaj ke liye yehi likhna tha.