Yoga
I've been to group classes. I've gotten a few lessons from a private Hatha teacher. I've experimented with different sequences.
98% of the yoga I do is from this beginner Hatha class on YouTube and it's been that way for years.
Yoga is not about exercise or making yourself flexible; although those can be added benefits. Yoga is about cleansing burdensome energies from your body and spirit, inviting fresh energy in to replace it, and experiencing the well-being effects mentally and physically as a result.
The word yoga means "union". It's about reuniting you with the divine... a.k.a. your true self :)
In Sanskrit "Ha" means sun and "tha" means moon. Hatha yoga also has to do with balancing the masculine and feminine energies flowing inside of you.
After a really good practice you can get a reminder of what you truly are again. Thoughts dissolve. The body ceases to exist. It can be transcendent, peaceful, and euphoric.
I've found the Sirsasana (headstand) to be super beneficial as well. Letting all that blood rush to your head for once has physical and mental benefits; it's also super fun (especially when you topple over and eat shit). I'll usually do one at the very end of my practice. I went D.I.Y. on that one and you can do the same by searching around.