Complex sentence: At the age of 18 he began working as a common laborer, which he stayed until his death, though he earned a reputation as a very reliable worker and his business agent would later describe him as one of their best, somebody who was never late.
Split into simpler sentences: At the age of 18, he began working as a common laborer, which he stayed as until his death. He earned a reputation as a very reliable worker and his business agent would later describe him as one of their best, and somebody who was never late.