The Founders' definition of "happiness" came from Sir William Blackstone's 1765 biblically based definition: "[God] has so intimately connected, so inseparably interwoven the laws of eternal justice with the happiness of each individual, that the latter cannot be attained but by observing the former; and, if the former be punctually obeyed, it can not but induce the latter."
Happiness and eternal justice (obedience to God's law in creation) are inseparable. The founders of our nation understood "happy" to mean "blessed." They knew that true happiness depends on one's obedience to God's commands (check out Jesus' Sermon on the Mount in Matthew 5). God's commandments are not random demands, they are instructions from the One who made and sustains the universe.
The Declaration of Independence protects our inalienable right to pursue true justice and God's blessings -- not necessarily our every desire.
I expect a huge majority of Americans have no understanding of that simple concept and its relation to our prosperity. It’s something that should be taught if we are ever to turn away from the nanny state.