No one in our society needs to be told that exercise is good for us. Whether you are overweight or have a chronic illness or are a slim couch potato, you've probably heard or read this dictum countless times throughout your life. But has anyone told you-indeed, guaranteed you-that regular physical activity will make you happier? I swear by it.

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.'

Last but not least, the happiest people do have their share of stresses, crises, and even tragedies. They may become just as distressed and emotional in such circumstances as you or I, but their secret weapon is the poise and strength they show in coping in the face of challenge.

The practice of gratitude is incompatible with negative emotions and may actually diminish or deter such feelings as anger, bitterness, and greed.

Happiness is not out there for us to find. The reason that it's not out there is that it's inside us.

The combination of rumination and negative mood is toxic. Research shows that people who ruminate while sad or distraught are likely to feel besieged, powerless, self-critical, pessimistic, and generally negatively biased.

Thus the key to happiness lies not in changing our genetic makeup (which is impossible) and not in changing our circumstances (i.e., seeking wealth or attractiveness or better colleagues, which is usually impractical), but in our daily intentional activities.