I don't remember the last time I worked late nights or even more than 10 hours. My window of productive working hours is from 4 AM till 5 PM in the evening. I work usually 6-8 hours when I have the peak workload and frankly I work 4-5 hours most of the time. Am I working too less? May be. Is it bad thing? May be. Will I be able to achieve a lot more if I put in more hours? I don't think so. I am happy with whatever I doing and that is more important. I look at people these days, mostly working professionals or startup guys and sometimes I feel guilty of not working like them. I want to confess that although I am good in what I do but I don't like working for long hours. I prefer finishing my work as soon as possible and have fun for the remaining day. Now you must be familiar with the non sense logic of love what you do and you will not feel like working. That is stupid. There are trillions of things to do in life and work, you can't possibly love each and every single thing. Things that give you most value or reward may not be interesting, it may be boring also but you still have to do it.
There is nothing wrong in doing things that you don't like. I say start doing those boring things and you would start liking them. Generate interest. I do feel guilty sometimes of not working enough. There are days in the week when I just don't do anything at all and few days I work religiously from 4 AM to 5 PM, but I never really work more than 8 hours.
I like planning things and believe in doing things efficiently. Even if I have to do something beyond my work, like a side project or learning a new skill, I plan it and do it but I never stretch. Everyone works differently and people have differently level of intelligence. I know few people who don't rest until they have a task to do, same is the case with me. When I have a delivery to make, I give my 101% and even more. I think about that task all the time, but I hardly work for long hours. It is not like I can't, I can certainly work without sleep for 3 days, I have done that in the past but when you plan your work really work, you would hardly need to do that.
When I was struggling in my early days of career, I used to freelance in my free time and then after few years I started my company and I struggled a lot, but even in those days I never worked long hours. I planned my week and what work I would do everyday in advance. I tried several tools but keeping a notepad is the best. For instance after company back from job I used to spend at least 2 hours everyday on other projects and on weekends I used to give additional 8 hours. I used to take office cab and I tried my best to utilize my time reading books. Even in the office I didn't make lot of friends. Eating lunch with people, meeting over tea is all great but kills not only time but your energy and most importantly your mind has limited energy every day. If you fill your mind with unnecessary information then you will not feel like working after coming back from office. Try to isolate yourself when you have to achieve something.
These days I am more on a free mode where I don't plan much and I work as things come. I enjoy it. I do work at my own sweet pace but I have earned it by working consistently over the past 15 years. I do give myself few light months of no-plan mode every now and then. It relaxes me. I work on plan-mode from March till August this year and from September onwards I am working quite comfortably. Ask yourself what will you achieve by working 15 hours every day? Unless you are sure that your 15 hours per day will give you lot of money or satisfaction, don't do it. It is not worth it. Instead do other activities like exercises or play some sports. Join some meetup club and go there once a week. Meet regularly with your friends and give time to your family. There is nothing wrong in enjoying life. Work not hard but consistently, that is my rule.