But one of the main reasons why Denmark does so well in international happiness surveys is the welfare state, as it reduces uncertainty, worries and stress in the population. You can say that Denmark is the happiest country in the world or you can say that Denmark is the least unhappy country in the world. The welfare state is really good (not perfect, but good) at reducing extreme unhappiness. Universal and free health care, free university education and relatively generous unemployment benefits go a long way towards reducing unhappiness.
Adults are not supposed to play. We are supposed to stress, have worries and be too busy dealing with life's problems. But according to a study undertaken by Princeton University and led by Alan Krueger, Professor in Economics and Public Affairs there, we are happiest when we are involved in engaging leisure activities.
If a city is designed in a way that makes a long drive to work necessary, we harm the social health of that city. If a lot of people cycle, it's probably an indication that you live in a healthy neighborhood. This is something that should be seriously considered in urban planning, if you want to ensure a neighborhood togetherness and trust among locals.