To understand the event "My feet are tired.  I have been standing up all day.", it is important to know that Build a model using Data base of information on Standing, to link factors like economics(price/ pay/ returns on standing i.e money    if you are a thief breaking into a bank, Medicines/drugs available to enhance performance (doping in olympics-tolerance or increasing threshold of pain, Cost/benifits analysis of price of drugs, / side effects.old of pain