There are three types of things that you should keep. The first are things that spark joy for you personally, such as a favorite pen, a memo pad with a design you like, or a photo of your loved ones. The second type are things that are functional and aid your work, things you use frequently like staples or heavy-duty packaging tape. They don’t particularly spark joy, but they make your daily work easier. Just having them lets you relax and focus on your job.
The third type are things that will lead to future joy. Receipts, for example, don’t inspire much of a thrill, but they have the obvious merit of allowing you to be reimbursed when you use them to claim expenses. Papers related to a project about which you feel little enthusiasm will, if you complete that work conscientiously, be a plus for your career. And if being valued for your reliability is part of the dream you want to realize, this will also bring you future joy.