Consider every action that can be taken at this moment. For each possible action, consider every possible future (out to infinity) weighted by it's likelihood.

Consider every action that can be taken at this moment. For each possible action, consider every possible future (out to infinity) weighted by it's likelihood. There are exclamation marks because some of these terms present minor practical problems. The whole, all possibilities out to the end of forever part of it, is easier said than done.