keen on doing

keen on (someone or something)

Especially excited about or interested in someone or something. I'm glad that Jimmy and Lena are finally going on a date, since he's been keen on her for months. Traveling to Tokyo last July made me really keen on learning Japanese.
See also: keen, on
Farlex Dictionary of Idioms.

keen on doing something

willing or eager to do something. Dave isn't very keen on going to the opera. The children are keen on swimming this afternoon. Shall I take them?
See also: keen, on
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.
See also:
  • keen about (someone or something)
  • keen on
  • keen on (someone or something)
  • be keen on (someone or something)
  • do the unthinkable
  • good to hear your voice
  • (it's) good to hear your voice
  • be glad to see the back of (someone or something)
  • be glad to see the back of someone or something
  • be glad, etc. to see the back of somebody/something