I agree you can do things that affect your relative happiness, but the key here is that it's YOU who must know what the things are - everyone have different needs and you can't fit all in one model. Some prefer to have interesting, but lower paying job, some doesn't care as long as it pays for their hobbies - and both can be happy, but switch their lives and both will be miserable. So if one would give advice to the other on how to be happy, it wouldn't help a bit, because they've different perspective on life.