Some days, his job requires the agility and tenacity of a border collie.

Spending so much time on a single project requires tenacity, even a crush on one's subject.

This exuberant self-help book argues that creativity requires discipline, tenacity and the total investment of body and mind.

To be willing to learn through failure - failure that cannot be hidden - requires tenacity and courage.

Troops battling in fortified areas require special tenacity, endurance and stamina.

It is a place, this desiccated land in northern Kenya, where living requires severe tenacity.

It requires courage and tenacity to accomplish every project.

"It required such tenacity and patience."

To survive has required tenacity.

It requires tenacity, patience and optimism.