Sleep less but sleep twice a day; Winston Churchill used to take an afternoon nap so he could work late into the night and claimed to fit one and a half days into one.
Delegation & synergy; getting other people to do the work means that together you can do so much more.
Take at least one more day off a week; rest will make you more productive.
Exercise and eat well; keep high glycemic index foods (sweets, breads, pastas, fast food) to a minimum & you will increase your energy and endurance.
Have a clean & organized environment: you won’t spend so much time looking for stuff.
Have more than one computer; If you work with computers and spend a lot of time WAITING for visual effects to be rendered, get another computer and you may double your productivity.
Plan your day the night before and you will wake up knowing exact what you are going to do.
P:S: Please add any other suggestions