Student or Learner
I worked with a man from whom I learned very much, not only about the job but the life. From my first day at work he was very friendly, always willing to help and explain everything. Although he worked at two jobs (he had (has) a large family of five children) he never looked exhausted or unhappy and I never saw him complaining…(which word is more appropriate to say quite the reverse here)…he was very cheerful and hopeful.
Thank you in advance!
"Quite the reverse" fits perfectly, "has" could also fit instead of "had" but I prefer "had".