Define your priorities according to what you can do

One of the principles of this approach is to sort out and select things to do asking yourself : "Which action can I take here and now? ". Actually for David Allen what directs the choice of a task are its intrinsic conditions for carrying it out, before any idea of a prioripriority. Therefore each task goes along with criteria which allow to choose the one that is going to be done here and now :
1. environment : place (I can do this task only if I am at my office) or person (I can do this task only if I am with Steven) or a tool (I can do this task only if I have a computer connected to the Internet)
2. available time : I need such time to carry out this task
3. available stamina : to carry out this task I must be in tip-top form, or very careful or else I can carry it out even if I can't think properly.
4. priority : priority of the plan or of of the task.
But priority is only taken into account in the end, it does not work out the task but it works out the possible task corresponding to environment, available time and stamina that I will finally.
I decide to carry out a task only if I can really do it.