Since the title is "Thing" I'm going to focus on things but in general what I can't live without are people close to me along with pets (pets are people to me but still) but let's dig into that material part of life, shall we?
One thing I can't live without is; My Fandoms.
My fandoms like shows, movies, Harry Potter and so on has a mayor part in my life (which most of you know) but it makes me function better. And it's a life saver for me when I'm struggling more than usual with life due to depression and other things. My shows don't just give me happiness but they also give me structure in life, espically when a new season is airing I'm better at having a daily routine to stick to, it makes it easier to focus on things outside of it as well. And lets not forget all the amazing people I have met through a shared fandom. I wish I could collect them all under one roof and line them up to hug them forever and ever for all the support they've given me through out the years. Fangirl and Proud!