I spent, at a minimum, at least $500-$1,000 a month exclusively on my self improvement. Here is most of what I spend on, in no particular order:
Education (classes, books, courses, certifications, college tuition, seminars, etc.)
Private lessons for languages, musical instruments, sports, etc.
Personal hobbies and passion projects
Crest whitening strips (great when in a pinch), Invisalign, professional whitening, preventative dental care, prescription whitening products from my dentist
Investments such as index funds, REITs, ETFs, CDs, individual stocks, commodities, appreciative luxury items, precious metals & gems, etc.
Organic food, vitamins, supplements, high quality healthcare, therapy, massages, prescriptions (Rx skincare, etc.)
New glasses & contacts (getting some bayonetta glasses from Burberry soon, very excited)
Sports, gym membership + sauna, hot yoga, Pilates, kickboxing, tennis, skiing, dance, etc.
Personal care such as bath/shower products, body care, haircare, skincare, makeup, brightening eye drops, perfume, etc.
Travel, events, concerts, festivals, etc.
Shopping (clothes, accessories, home goods, etc.)
Eating out at restaurants and going to coffee shops
Beauty treatments such as manicures, pedicures, waxes, brow tint & threading, salon blowouts, hair cuts & colors, facials, lash lift & tints, vitamin IVs, etc.
Regular visits to my dermatologist, dentist, psychiatrist, eye doctor, primary care physician, gynecologist, and any other specialists
Semi-regular appointments with a personal trainer, holistic nutritionist, and dietitian
I don't do all of these every single month, but most of these are recurring throughout the year and budgeted accordingly. Eventually I might add in more intense cosmetic work like medspa services, Botox, etc. If you can find a workplace with a great benefits package such as high quality healthcare, an HSA/FSA, health & wellness reimbursements for the gym, disability & life insurance, etc. I would highly recommend it and max out all the benefits you can.