Persevere

Courage and perseverance have a magical talisman,
before which difficulties disappear and obstacles vanish into air.
- John Quincy Adams

The habit of persistence is the habit of victory.
- Herbert Kaufman 

All endeavor calls for the ability
to tramp the last mile,
shape the last plan, endure the last hours toil.
The fight to the finish spirit is the one...
characteristic we must posses
if we are to face the future as finishers.
- Henry David Thoreau

The difference between perseverance and obstinacy is
that one comes from a strong will,
and the other from a strong won't.
- Henry Ward Beecher

Patience, persistence, and perseverance.
A little more each day,
a little better each day.
- Jonathan Lockwood Huie

Further reading: Stand Up To Your Obstacles

Emulate the Patience of Nature

Mental Attitude

Realizing Success