I want to use this sentence on my cv, but I don`t know which adjective I should use.
I have very a large/big/lot of motivation.
This is not an answer to your question, sorry. But I can't let you fall into that pit.
I strongly advice against putting such rubbish in your CV. The reason it's rubbish is simple: it's a code word for "desperate". And you really don't want to let anybody know before they see you that you're desperate for that job/position/occupation/career. Your CV should be attractive, yet dignified.
Try to imagine yourself the hiring manager. Would you actually consider talking to a desperate candidate? Do you really need a desperate member on your team?
There is plenty of online sources that will (for free) tell you how to create a decent CV, what to say, how to say it, et cetera. Use them.
Good luck in your search!