@cheong: When you are younger, your body can take it, and you effectively are learning on the job. 60 hours is not a lot if you are >35, if you said 80 hours, then I might start to acknowledge that you are working very hard.

After a while, you will find most of the time, removing yourself from the problems, having a long break, and doing other things like hobbies helps solve problems that world take 120hrs in a week.

If it is a short term project 3-9 months, and you have had a month or two off, then it is manageable, being relaxed and stress free is the secret.