The challenge of sitting down to do the work.

The mind says that we need to figure everything out before we sit down. It gets distracted by some genuine and some invented urgencies, forcing us to delay sitting down. The more we delay, the more stressed we feel, and the less likely we are to sit down and start the work.

The key here is to look at the challenge as a physical one rather than an emotional one. Steven Pressfield says, "Put your ass where your heart wants to be". When the clock chimes and it's time to work, our heart wants to be sitting at our desk and doing the work.