Motherhood and Apple Pie...
The goal of my life is to be happy. Happiness, to me, is like a pie cut into different sectors:
Family
Friends
Relationships
Greater Good
Financial well being
Career
Knowledge
Skills
Creative Pursuits / Interests
Rest & Relaxation
Prayer & meditation
Health, exercise/sport & diet
Fun & entertainment
The key is to channelize the energy that God gives us into different sectors of the pie, be efficient and effective and thus realize our goals and be happy. Now, the optimal distribution of energy is dynamic and changes as we progress through different phases in life.
I think the difference between happy and not so happy people (keeping this particular model in mind) is people who are able to anticipate the changing phases and who are able to channelize energies in the right proportion.