쉽게 바뀌진 못할걸.

A: I’m giving up all my bad habits. I need a fresh start.
B: 쉽게 바뀌진 못할걸. I’m skeptical.
A: I’m being totally legit. I swear on the “Good Book”.
B: Well, I hope you can do it, but let’s wait and see.

A: 내 나쁜 습관을 모두 버릴 거야. 새롭게 시작할 필요가 있어.
B: A tiger can’t change its stripes. 난 회의적인데.
A: 난 정말 진심이라고. (성서를 두고) 맹세해.
B: 해낼 수 있길 바래, 하지만 지켜보자고.

[Additional expressions]
*I’m giving up all my bad habits.
– I’m stopping all the bad habits I have. / I’m getting rid of bad habits.
*I need a fresh start.
– I have to start all over again. / I need to start again from the beginning.
*A tiger can’t change its stripes.
– You can’t teach an old dog new tricks. / You are who you are.
*I’m skeptical.
– I have my doubts. / I’m not very confident that you can do it. / I don’t have much faith.
*I’m being totally legit.
– I’m being honest with you. / I’m telling you the truth. / It’s true.
*I swear on the “Good Book”.
– I give you my word. / I can make you an oath. / Right hand to God.
*I hope you can do it.
– I wish you lots of luck. / I’ll keep my fingers crossed for you.
*Let’s wait and see.
– Let’s see how things go. / We need to see how well you stick to your word.