work on

verb2

1. •
   To apply mental or physical effort to (something) in order to shape, form, improve, investigate, solve it, etc.

   • John's in the studio working on the plans for the new house.
   • I've been working on this problem for several days, but I still haven't figured it out.
2. •
   To exercise influence on someone.

   • Leave it to me. I'll try to work on the boss to give us the day off.