For example, I know I'm getting older, time is limited, and I'm mortal. Taking LSD and looking in the mirror and really seeing myself more objectively, all the wrinkles and saggy skin, the meat of my body hanging off my bones, makes my aging far more tangible and immediate than I can normally conjure. The trick is afterward maintaining that feeling and using it to make decisions about health, prioritizing things that are important, and dropping things that won't matter to me in 20 years.
If I had anxiety issues or deep trauma to work through, I'd absolutely want to use psychedelics in concert with a trained professional to minimize the risk of having things go wrong and to get help in figuring out what the trip meant to me (or "integrating" in the parlance).