To be behind the eight ball means to be put in a difficult position. But the sign in this photograph appears to be more in the motivational vein, such as YOU CAN DO IT! Or, NEVER GIVE UP! Or maybe it resembles a political ad. On the other hand, some might read as a suggestion to get into a difficult position, such as getting in front of an onrushing bus.
Speaking of motivational phrases and politics, when you mix them together Martha Washington appears and speaks the following (remember, they buried her alive):
“I have learned that the greater part of our misery or unhappiness is determined not by our circumstance but by our disposition.”