Spoon theory is a useful way of explaining how mental and physical energy is rationed each day, through the eyes of someone with chronic illnesses or disability.

To snippet from Wikipedia, emphasis mine:

The spoons helped Miserandino to show the way that people with chronic illness often start their days off with limited quantities of energy. The number of spoons represented how much energy she had to spend throughout the day.

As Miserandino’s friend stated the different tasks she completes throughout the day, Miserandino took away a spoon for each activity. She took spoon after spoon until her friend only had one spoon left. Her friend then stated that she was hungry, to which Miserandino replied that eating would use another spoon. If she were to cook, a spoon would be needed for cooking. She would have to select her next move wisely to conserve her energy for the rest of the night.