Four friends embark on a thrilling adventure as they embark on a journey of a lifetime.

这句话表达了四个人一起旅行的概念，强调了这是一次充满冒险和兴奋的旅程，如果更侧重于轻松愉快的氛围,可以这样说：

"Four buddies set off on a fun-filled trip, ready to explore new horizons and create unforgettable memories."

这个表述强调了旅行是为了娱乐和创造美好回忆，更加符合休闲游的氛围，具体的表达还可以根据旅行的目的、地点和预期的活动进行调整，如果是户外探险，可以说："Four adventurers hit the road for an epic journey through the wilderness." 如果是文化之旅，则可以说："Four travelers embark on a fascinating cultural odyssey, immersing themselves in the rich tapestry of history and tradition."