Reflect on the fact of it daily, not in the abstract but in a personal way: this very body will die. When it's useful, in my experience, is when this effort shepherds motivation into play, both for perpetual presence of mind as well as for renunciation of sensuality. These become preferable, basically.
It's an applied seeing of anicca, but in this case - as in every case - it's important and useful to balance the contemplation: calm observation, not just observation and not just calm.
I have gained by keying death-mindfulness to feelings of boredom; one can snap out of a mental fog in short order, this way. It's also a great way to pass the time on public transit instead of trying to ray-gun metta into everyone, which can eventually dovetail into a more emanating (exuding? effervescent?) metta practice which enforces equanimity about where metta can land, as it were.