Some hikes are on level ground. Most, though, are on a grade of some kind. Uphill walks take more energy and time for a net of less distance. Downhill walks are faster and easier, and often take us father in the time we have. Some days we sit down (or stand) at our desks and begin to work, and find that everything we do is an uphill climb. Tasks take longer than expected. We get less accomplished. We're exhausted at the end of the day and we feel like we barely accomplished anything.
Other days are different. We breeze through our lists, complete a few items from the following day's list, and still find ourselves with a bit of free time at the end. They energize us and make us feel like we could do this forever.
I have yet to find the secret formula for making sure each day is a downhill day, but I'm working on it. In the mean time, every time it happens, I'm trying to enjoy every moment of it.