Start your day with the most important work. Invest 100 % of your effort on that important work and then consider putting an extra 10 % on the same work to ensure you have leveraged it fully.
When you accomplish an important task very well, it creates a spring in your step which is bound to impact other important work in the day.
Therefore invest 110 % focus on your most important work first thing in the morning and witness the excitement and energy flow into other areas of the day.