Unless the person is depressed, contemplation of death is considered a good—even essential—practice for Buddhists.
“Analysis of death is not for the sake of becoming fearful but to appreciate this precious lifetime.” —Dalai Lama
I had an experience with this contemplation recently.
A bad sign made me decide to see a doctor. She said, “Full disclosure, this could be serious.”
I was calm because I already knew that. The clinic took blood and did some other tests.
I went home and thought about what might happen. My ensuing contemplation of death had not been planned but it did “concentrate the mind wonderfully.”
In doing so, it relieved me of all of my usual worries and fears. For days I was able to float above my life and look upon (almost) every moment as unique and valuable.
I loved this state. Everything I don’t like about myself went away.
Then my symptoms disappeared and I realized I was not going to die soon, at least not from what I had thought.
And almost immediately my concentration changed and the stuff I don’t like about myself (almost all) came back.