I'm so sorry you've lost your friend 💐
I have always lived like this as much as possible, partly because a friend in my year in sixth form died very suddenly aged 17, and I never quite came to terms with him not getting to experience everything the rest of us did in young adulthood and the rest of life. I lost my Dad five and a half years ago and that's made me really appreciate that we only get one life.
So... big stuff for me has been quitting my job to finally run my creative businesses full time, working on my own schedule (hence still being awake at gone 3am), having pets, buying my house, saying yes to mad stuff like a banger rally across Europe, choosing to live alone, stay single and not have children despite what everyone often tells me I should be doing instead.
Smaller stuff which doesn't rely on anyone else, doesn't require chucking your life on a fire and has had just as much impact on my happiness - burlesque classes, a ridiculous (but not expensive) car for a decade, a collection of beautiful bedsheets, a milk frother for proper hot chocolate, making time to read, writing with fountain pens (my favourites are kaweco sports with a broad nib, under £20) and finding my signature ink colour, spending as much time as I can by the sea or the river, my kayak and going out paddling on my own and also with friends, going to steampunk and events with like-minded weirdos in costume, making art, wild swimming, wearing exactly what I want with zero regard for fashion, occasionally ordering a whole cake or cheesecake just because... a nearly endless list of things, none of them massively spendy, which mostly can probably be summed up by saying do what you fancy, define your own indulgences, and use the stuff you're saving for 'best' all the time 😁
And I make an effort to spend as much time with friends and family as I can - but I like having the other things to live fully even when other people aren't available.
Lots of people will probably say travel - I'd say exploring, which I'm currently really enjoying doing in the UK, reasonably close to home. I have caring responsibilities so am unlikely to go far for the next few years, but there's so much to discover here once you start looking. I have a list of places I want to visit which are inspired by or featured in favourite books.
If you're a theatre person, sign up for the mailing list of your local one - I've seen some amazing productions (dance is the thing I love most) in local theatres and you can often book last minute.
And I love to document all of these adventures, big and small - sometimes in a journal, sometimes on my blogs and sometimes in scrapbooks or photo albums, but there's usually a record somewhere (and a massive box of things to put in a scrapbook or album when I have time!).
That was a bit longer than planned but well done if you read to the end. I hope you find a whole list of your own of things that make your life full and happy and joyful x