informal: 나 다이어트 중이야 formal: 저 다이어트 중이에요

Thank you for your helpful explanation, Michael!

그녀를 다시 한 번 안고 키스할 수만 있다면 내 인생이라도 바칠 것이다

I have some foreign friends who learning Korean. It is hard to speak like a native but I don't think Korean is so hard to learn. Although it sounds really awkward, if you know some basic rules you can speak some. If you really feel like you want to learn it, that would help you.

As Pacsal said, you can say 저는 수줍음이 많아요 or 저는 부끄럼을 많이 타요. But we don't say 저는 수줍음이 많아요 when you talk about yourself. I never seen before. When you want to say you're shy of strangers, you can say 저는 낯을 가려요.

금도끼 은도끼 선녀와 나무꾼 흥부와 놀부 해님 달님 젊어지는 샘물 효녀 심청 콩쥐 팥쥐 요술 항아리 냄새맡는 값 토끼와 자라 별난 재주 삼형제 etc.. Hope this helps

You are welcome ^0^