Let us leave these problems for the moment and look at the next verse. Commenting on the third verse, Rashi explains that Moshe rushed to fulfill G-d's command, although he knew that it would bring his life to a close. In theory, Moshe could have waited on making war against Midian and prolonged his own life. However, doing the mitzvah was Moshe's primary interest. For Moshe, there is no greater life experience than doing G-d's command.
Every life ends, that is of no concern.
However, what we do while we live within the time granted us is of concern. In doing mitzvot, there is a notion of zrizut, alacrity. Every obligation should be done as soon as possible. We observe this in the way in which Avraham arose early in the morning to take his son Yizhaq to be sacrificed. There should be no procrastination or hesitation in serving G-d.