There's another ship. It has a captain and crew but no destination is set. Where is it going?
There's another ship. It has captain, crew, destination but no course is set. Where is it going?
There's another ship. It has captain, crew, destination and a course set. Everyone is ready to go and intends to go. Where is it going?
Only one of these ships will set sail, leave the harbor, reach a set of map points, follow that course and arrive at its destination. Regardless of being driven off course due to bad weather or other circumstance, only one has a real chance.
"Perseverance cultivates a sense of purposefulness that can create resilience against or decrease current levels of major depressive disorders..."
Sort of. Purpose means perseverance is useful. Lack of purpose means perseverance, resilience or even the least effort can be wasted.