Tanzania, April 13 -- Success is defined differently by different people. For some, success means excellently accomplishing defined goals within timeframes. For others, it's having an active social life and learning to positively handle consequences when friends become foes.

Regardless of how one defines success, American author Robert Collier gave a superb clue. "Success is the sum of small efforts, repeated day-in and day-out."

So, who were the most successful couples in history? Is it Cleopatra and Julius Caesar? Queen Isabella and King Ferdinand, or Queen Elizabeth II and Prince Philip?

Some think it's Martin Luther and Katie. Nonetheless, here are some clues on how spouses can unleash supersonic success in a relationship:

Seeking...