First, the most important thing we can do is to be realistic in what we can achieve. It may be that it's just not possible to write that book review and revise that article, or submit that entire dissertation chapter during the final part of the term. We may have to make difficult choices about what is most important, and we may have to face the fact that our avoidance of certain tasks and our reluctance to define them is a way of denying the reality that we have to make those choices. If we keep a perpetually unfinished to do list, we can continue to believe in the illusion that the whole list will get done.
The problem is that perpetuating that illusion never really works, because there will always be a part of us that realizes we have more to do than we think we do, and that's where the guilt comes from. That's when we feel the weight of unfinished tasks. So while it can be incredibly painful to admit to ourselves that what we're attempting is impossible, it's often what we need to do in order to move forward and actually start finishing the tasks.
Maybe it's not realistic to submit that whole dissertation chapter, but it is realistic to write five or ten more pages of it. We might need to let that book review go and focus on the revise and resubmit instead. And maybe, if we carve out just fifteen to twenty minutes a day during the "crazy" part of the semester, we can still finish that thesis. By setting and defining concrete goals we can still move forward towards completing those larger tasks.
Finally, it's important to realize that while there will always be something more we can do, it is unhealthy and counterproductive to work all the time. The end of the semester is characteristically a very busy time, and you just might not be able to expect too much of yourself. Forgive yourself, accept your limitations, and then make plans for how to approach the situation differently in the future. You’re the only one who can release yourself from the weight of your tasks. You're the only one who can lighten your load.