Not let the grass grow under your feet
Definition 1 of 1
Pro Tip 1/3Urgency Implication
Indicates immediate action is necessary, suggesting a sense of urgency or impatience. 
The manager insisted we not let the grass grow under our feet to meet the deadline.
Pro Tip 2/3Motivation Encouraged
Encourages motivation, typically used when there's risk of procrastination or laziness. 
To win the competition, they couldn't let the grass grow under their feet.
Pro Tip 3/3Metaphorical Visual
Visual metaphor of unmoving feet so long that grass grows, implies inactivity or delay. 
We'll miss our chance if we let the grass grow under our feet!