fair enough, just know that sometimes some people just don't want to live, and that's actually ok
maybe there's just analytically nothing in particular that makes us want to keep going
again it's sad for the people around that person, maybe it's not what's considered "normal" but still ok. those people will be sad for a couple years, but "time heals all wounds"
if you do want help to stick around, my advice would be if possible to pick up a physical hobby like a local martial arts place, rock wall climbing, downhill mountain biking etc. just being out and about and then working the body itself releases happy chemicals, and you're more likely to stick to it than say going to a gym. then self confidence will increase, attractiveness and a few other things that will make life much more enjoyable in every aspect
if not, then i had the same idea about carbon monoxide, but you can use charcoal and a small/portable barbecue to put in in and light up in a small room like bathroom for better effect