Word or phrase for "not being into something that much as the other person thinks"

Question

Is there a word or phrase used for describing something that one does not want to do as much as another person thinks? For example,

I'm not ______ to do that as much as you think!

Edit: Thanks for all the answers and the editing of my original question :)

At first I did not mention this but it can give a clue, or there may just not be a word for what I am trying to say. I am actually looking for a word with a very specific meaning in my native language. It is said when someone senses that the other person seems to be looking down on him/her, although not openly. So this person needs to remind that he/she has the dignity for not desiring the thing the other person thinks he/she desires.

Answer 1

In British English there is a word that fits this quite well.

Keen - To show an interest in or be enthusiastic about something. Much like being into something.

In this situation I would say: "I'm not too keen on that." - Meaning that I'm not interested or excited about it.

You could also say "really not keen" if you want to be more forceful.

Cambridge Dictionary

Answer 2

• "I'm not really that much into it"
• or a rather unpolite version to express ones unwillingness to do something: "I can't be bothered"

I'm afraid I can't think of any phrase that matches exactly what you want: expressing that the inclination is much less than the other person thinks.

Answer 3

I deign not participate in such as you ask!

Definition of deign, intransitive verb: to condescend reluctantly and with a strong sense of the affront to one's superiority that is involved : stoop

would *not even deign* to talk to him

One iconoclastic architect, for example, doesn't deign to speak of 

bathrooms. —Carol Vogel

transitive verb : to condescend to give or offer

never so much as deigning a glance —George Meredith  [Merriam][1]

Answer 4

I'm not inclined to do that as much as you think!

ODO:

incline
VERB

1 (usually be inclined to/towards/to do something) Be favourably disposed towards or willing to do something.

‘Even children seem to be more inclined towards indoor activities and television rather than playing outdoors.’

Answer 5

I have a suggestion that is more colloquial in flavour:

down to do something.

I could only find The Free Dictionary as a verifiable source for the same. It defines the idiom as:

be down to (do something)

To be ready, willing, or eager to do something.

I'm down to play a quick game of soccer if you are.

I am so down to see that movie tonight, I've been waiting for it to come out for months!

A: "You want in?" B: "Yeah, I'm down."