you are part of everything around you. and if you don't, alienation.
most of us separate ourselves for protection. remember how everything seemed to hurt so much in childhood - criticism, failure - resulting in shame? i swore i'd never forget the vulnerability and pain of not having boundaries.
gradually we build walls to protect ourselves. nobody wants to hurt like that when older (that's a kind of madness, all the symptoms of insanity acting literally like a child as an adult without control.)
how does anyone survive high-school? if you haven't read it, i recommend this book:
what i mainly remember from it: that time in our life creates unforgettable memories due to the anxiety. in a sense, it may be a return to complete presence, vulnerable to all the emotions of a two-year old. sex does it, certainly. the new surge of hormones driving us to make babies - in old societies people married a lot earlier. infanthood and high-school intimately related.
getting back to now takes discipline and risk. actors and athletes find it in fear, effort, and concentration. zen masters do it by not letting thoughts dominate their existence. personally, i find the best thing is to walk on the beach. as i get back in my car, i'm amazed at how relaxed i feel.
the return to youth isn't easy without going crazy. of course, that's the attractiveness of drugs. every high simply being completely where you already are. unfortunately, it generally takes it's toll on the body. for all our envy of tribal life, those people died a lot earlier, and ingesting powerful hallucinatory roots didn't help. short and intense, long and boring, take your pick