The field of economics lends itself to analysis of human activity beyond the scope of dollars and cents. Social-Cost Benefit Analysis is one economic method of evaluating projects which allows and in fact makes valuing leisure time standard procedure. Opportunity cost is a fundamental in economics, where each allocation of resources has an associated cost. That cost is the best alternative forgone. It sounds more complicated than it is.
Someone gets a job.
For example housework, gardening, volunteering or simply their leisure time. The assumption is normally that the value of their labor exceeds the perceived loss on their part of the alternative activity, otherwise they would not work. In Social-Cost Benefit Analysis, analysis of government plans to expand the MacDonald Bridge in Halifax would include the value of time saved as commuters get to work faster. A monetary value is placed on their time. However, another value might be placed on pollution generated by additional traffic on the bridge.