If we observe genuinely happy ...

If we observe genuinely happy people, we shall find that they do not just sit around being contented. They make things happen. They pursue new understandings, seek new achievements, and control their thoughts and feelings. In sum, our intentional, effortful activities have a powerful effect on how happy we are, over and above the effects of our set points and the circumstances in which we find themselves. If an unhappy person wants to experience interest, enthusiasm, contentment, peace, and joy, he or she can make it happen by learning the habits of a happy person.
 Sonja Lyubomirsky

Quotes from the same author

If we can accept as true that life circumstances are not the keys to happiness, we'll be greatly empowered to pursue happiness for ourselves.
 Sonja Lyubomirsky
When we are fully mindful of the transience of things - an impending return home from an overseas adventure, a graduation, our child boarding the school bus for the first day of kindergarten, a close colleague changing jobs, a move to a new city - we are more likely to appreciate [be grateful for] and savor the remaining time that we do have. Although bittersweet experiences also make us sad, it is this sadness that prompts us, instead of taking it for granted, to come to appreciate the positive aspects of our vacation, colleague, or hometown; it's 'now or never.'
 Sonja Lyubomirsky
If you're not happy today, then you won't be happy tomorrow unless you take things into your own hands and take action.
 Sonja Lyubomirsky