In my language we can express the feeling of not willing to do something because we feel lazy about it. Is there any word in english that allows us to express this feeling?
The word I feel that is best fit for this would be:
- without interest, vigor, or determination; listless; lethargic:
a lackadaisical attempt.
- lazy; indolent:
a lackadaisical fellow.
Converting to a noun would be lackadaisicalness.
From my understanding of your question, unmotivated appears to be the closest match. From Merriam-Webster:
to give (someone) a reason for doing something
to be a reason for (something)
Motivated, the adjective form of motivate would simply inherit the definition of motivate in passive form, i.e. given a reason for doing something. So unmotivated would be not given a reason [or sufficient reason] for doing something. We're naturally lazy unless we are motivated to overcome that laziness.
Other options with differing nuances are reluctant, unenthusiastic, or uninterested, depending on the context. But unmotivated is about the closest I can think of.