A rat race is an endless, self-defeating, or pointless pursuit, like a mouse or rat in a running wheel, attempting to earn a reward such as cheese (salary), in vain.
Most people surrenders into working hard, for money, all through life, saving up for retirement, hoping they'll win the lottery and get time to enjoy the fruits of their hard life long labour. Changes are they wan't have much luck and quality time left with their loved ones, at the end.
One way out of the rat race, is to create new passive income streams, that generate money, while you do what you like the most. It could be renting out some space in your house or appartment, investing in stocks, creating novel ideas and make money out of it or do work that rewards you based on your results, rather than your time, which is a limited resource.