Backbreaking (adjective)

1. Demanding or exhausting physically or mentally, especially involving hard manual labor.
2. Exhausting, tiring, and causing strain or injury to the back.

Origin:

From the phrase 'break one's back' meaning 'to do exhausting, strenuous, or hard work'.

Examples:

1. The backbreaking work of harvesting crops in the hot sun was a daily challenge for the farmers.
2. The backbreaking journey over the mountains was a test of endurance for the hikers.
3. The backbreaking routine of carrying heavy loads took a toll on the workers' health.
4. The backbreaking schedule of rehearsals and performances was a challenge for the dancers.
5. The backbreaking task of cleaning up the aftermath of the storm was a daunting challenge for the volunteers.