Happiness: a thought experiment

So, a thought experiment...

Margaret Lee Runbeck is quoted as saying “Happiness is not a station you arrive at, but a manner of travel.”

a) What do you think about this take on happiness?

b) In this context, can sadness be accurately considered the opposite concept to happiness?

c) If so, is sadness therefore also a manner of travel? Or perhaps unlike happiness, can sadness actually be a destination towards which people seem to deliberately and/or subconsciously want to aim their life?

d) Bonus pondering: Recently read a piece that argued happiness should not be your goal, but instead contentment. Is that just another way to argue the same point being made here? Don’t try to be happy, just be content?

Note: I want to be clear that I do not equate being clinically depressed with being sad, any more than I equate being drunk or high with being happy. I know that adding in the element of mental health would impact this discussion greatly, so if that is a struggle you are dealing with, know that I am NOT suggesting you just need to change your attitude and everything will be okay. BUT even taking into account the issue of better or poorer mental health, is there any philosophical value to the distinction between happiness/sadness as destination versus manner of travel?

Curiosity levels set to high. Please discuss.