The idiom "Bite the bullet" typically means to endure a painful experience bravely. This expression originates from the historical practice where soldiers would bite on a bullet during a medical procedure without anesthesia, using it as a way to tolerate the pain.
Given the options:
The correct interpretation is "To endure a painful experience bravely".
Rearrange the following parts to form a meaningful and grammatically correct sentence:
P. a healthy diet and regular exercise
Q. are important habits
R. that help maintain good physical and mental health
S. especially in today's busy world