Have you ever met a very wealthy person who has been through a couple of divorces? Or a social butterfly that is in and out of hospital? It becomes obvious that if you spend too much time working, socializing, playing sport etc you may run into problems in one of the other areas of your life.
We are all gifted with the same number of hours in a day. The difference between happy and less happy people is the way they choose to spend their time. As noted above, it takes time to build a habit. If you spend all your time in one area of life, whatever you neglect has the potential to rip the carpet out from under your happiness.
Aside of the time needed to build a habit, according to Stephen R. Covey "Habit is the intersection of knowledge (what to do), skill (how to do), and desire (want to do)"