I almost drowned once when I was little.
I was at a pool party with some extended family for either a birthday party or fourth of July. I was too little then to know how to swim at the deep end but I decided I wanted to try since I was able to swim a little in the shallow end. I swam over with a pool donut and dipped down under the water completely. I couldn't swim back up as I flailed and looked up to the surface of the water. I could feel myself running out of oxygen as my head began to throb. After a short while the throbbing stopped and I was left with a euphoric feeling. I remember specifically thinking to myself, "So this is how I'm going to die, okay then." I was fully ready to accept my death as I stopped flailing. My dad jumped in shortly after I thought that and pulled me out. Once I coughed all the water out of my lungs, I got a deep breathe of air and the pain hit me all at once. My arms and legs hurt from flailing, my head hurt from the lack of oxygen and my lungs hurt and throat hurt as well. It was only pleasant before I got pulled out.
Another time I almost OD'd on meds.
I'm AFAB so I have to go through periods, which I hate. There are medications you can take to supress the pain and bloating from being on your period, similar to Ibuprofen or Acetaminophine. I use Midol, which can treat the period cramps and bloating as well as back aches and migraines. This one time I was on my period, I took some Midol. Now, with Midol, as with most other types of medication, you have to wait a certain amount of time before taking more. For this specific medication, it was 6-8 hours. After about 1 hour or so though, my cramps would get bad again, so I would take more. I did this about 6-7 times, taking 2 pills each time and began to feel light-headed and woozy. I wasn't thinking straight and felt extremely weak. I only stopped when a family member of mine walked in on my as I wasn't feeling the best and noticed this as well as recognized what was happening to me specifically. So she stopped me and explained what happened and why I was feeling the way I was. Even after that event I don't time myself after I take medication, but I tend to look at the time to get an overall idea of when I should take more should I need it. I usually forget though and end up not needing it anyways.
But yeah, those are the two times I've gotten close to death explained in detail