"Life is interesting, isn't it?" => 인생은 재미있지 않니? "Life" can be translated to different words depending on the context. - Life is interesting - 인생은 재미있다 / 삶은 재미있어. - My life is at risk - 내 목숨이 위태롭다 / 내 생명이 위험하다. - My daily life is fun filled - 생활이 아주 재밌어 / 내 생활은 아주 즐거워.

생활이 재밌지? Instead of 생활 you can use 목숨, 삶, 인생, 생명 as well, they all mea existing / living / life. If you want to say that particularly life is interesting (compared to other things), you replace 이 (the subject marker) by 은 (the topic marker). 재밌다 = 재미 있다, literally means funny but can also mean interesting. The ending -지 is equivalent to our "isn't it".