I've probably worked 100 hours a week for nearly all my working life, but most of that was as an entrepreneur. You don't have to enforce working hours. People who are motivated will work happily. In any case most real work happens in 4-5 hours a day, but you don't know when that happens.
I still find it difficult to call meetings as work but it takes more energy than what i call work. At some level this working x hours argument is ununderstable to me. When i play, I will play hard. When i work I'll work hard. I suggest you find your rhythm, and I hope you find success in that; major economic rewards will come, sometimes now, sometimes later, to people that don't watch clocks.