My job is less challenge... yet stress free.. work life balance and good pay..?

I have recently joining a new company. It is a bigger and well structure MNC compare to my previous employer. I received better remuneration package and benefits for a lower grade job with lesser responsibility. However, I found myself unhappy with the new job. The job scope which I am currently doing is much less challenge as compare to the previous job. I feel that what i learnt in my previous company cannot be applied in my current role. Instead, the things which i am currently handling is actually something which my ex-subordinate used to be handling. Recently, it is getting worst. I am listless in office and I lost all my passion on work. I feel guilty but I really don't enjoy doing the works. I am not sure what's the reason. Is it because of the people? the work? My current company is considerably a good company, but i find myself getting frustracted adapting into the company way of doing things and I started to miss my previous jobs and colleagues. (I am very closed with ex-colleagues but my current colleagues are just fine.. )

I am now considering to quit my job and looking for a new one. But I worry I may regret for giving up such a good job which is work life balance, easy and stress free yet good pay. My friends are all against my ideal for resigning and they are saying that I used to be working too hard and is time to take a slower pace in life. What should i do? I am really confuse and not sure what should i do next... can you share with me your experience if you have the same problem before.. thanks..