Both Breonte's and Johnz's answers are good, but there are some extra nuances of meaning. There is a very slight difference between 'keen to' and 'keen on'. 'Keen to' is more often used to express your willingness or desire to do something. It is used together with the infinitive of a verb. It also implies eagerness and/or optimism. Compare: "I want to learn English", "I am keen to learn English". In the first example, there is no inference of any emotional state. The second example ('keen to') suggests that the speaker is excited and happy about this activity. 'Keen on' is more often used to express that you like something. This is used together with a present participle of a verb. Again, it implies slightly stronger feeling. Compare: "I like running", "I am keen on running". In the second example, it sounds as if the speaker likes the activity ever so slightly more. There is also a very weak inference that the activity is more regular. 'Keen on' can also be used about objects or people. It is unusual to use it to describe your feelings towards an object, and using it about a person implies the early stages of romantic feeling. If you were to say, "I am keen on Suzanne" then it sounds as if you are planning on taking Suzanne on a date! Again, both Breonte and Johnz are entirely correct about the use of 'mean to', but there is a little more nuance of meaning. The past tense usage is more normal, as Breonte said: "I meant to do that" meaning "I intended to do that", "I did that deliberately". 'Mean to' can be used in the present tense to show your intention to do something in the future. This could be at any point in the future. All of these are acceptable: "I mean to beat you in this game of tennis", "I mean to visit him tomorrow", "I mean to visit England this year". Using 'mean to' in this way is slightly less usual, and raises class implications (in British English - I don't know about American English). It would more usually be used by upper-middle-cl