I need to work on the mind......
The duration question was most interesting. They concluded if you do 20 minutes per day, seven days per week, of whatever you do for exercise you will get the most long term benefit. The reason is attempting to do 30 minutes per day, results in a significant drop-out rate, by forty minutes the drop-out rate is huge, and by one hour per day statistically nobody is exercising (based upon the entire population). They even found you can get a benefit of two 10 minute intervals such as one in the morning and one in the afternoon.
The really big issue here is 20 minutes minimum per day. So if you do Owls Head today you need to do 20 minutes tomorrow.
I did this without missing a day for 18 months. I lost 65 lbs and hiked like a rabbit. Then I dropped something on my toe and broke the cycle. I have not been this goood for a while