Effort as Energy Expenditure

Effort represents an investment of a fixed resource, like calories.

For this reason, running takes more effort than sitting. It takes more calories and strains muscles and joints. If you run non-stop, you will need to eat more to stay alive, and you will wear your muscles out.

However, effort as energy expenditure does not fully answer why we struggle to take action, as effortful tasks, such as playing tennis, is more fun than doing nothing.