I believe that there is only a certain amount of tasks that humans can do where the prime motivator is that we have been asked or told to. I think these tasks use a very specific type of energy in the body and brain that needs to be replenished before it can be used again, and that this energy is different from the kind that is used when we are in a flow state where we want to do things. The motivation for these type of forced tasks is often money but it can also be things like household tasks or other obligations.
The interesting point for me is that how our mind interprets these things that we have to do can be informed, heavily, by how we frame them. A diary filled with tasks that NEED performed can easily begin to feel like work and tire us out, using up this precious slow renewing energy. The problem is that we chose to fill our diary with them so it feels like they shouldn't tire us out because we picked them, but they are still things we now feel obligated to do. If they don't get done, we will feel a similar guilt to missing a deadline or failing to deliver on a promise.
So how do we deal with this? The answer, in my mind anyway, has to do with motivation and minimalism. There are obviously some tasks that we will actually need to perform, but we can minimise the number of tasks that we perform in this way and try to ask the question "Do I really need to do this right now?". In this way we can simplify our lives and focus on the things that really matter and that we wish to do. Spending more of our time on things that we feel motivated to do allows us to tap into the state of flow that affords frictionless performance, fueled by our desire to work in the task space while in our current state of mind. Asking this question also allows us to weed out tasks that actually offer no value to our lives but we've been performing basically because we always have, or feel that we should.