For me ground work is everything and anything that happens between me arriving at the gate to turning my back as I walk out the pasture. So that's catching, leading, grooming, tacking, mounting, doing gates if needed, dismounting, untacking, spounging, feed time, and turning out again. Everything is potentially a training exercise, partly because Alli needs reminders every now and again she isn't the same unhandled, boysterous mare she was allowed to be 2 years ago.
Then theres things like backing, turn on the forehand, lowering the head- and raising it (useful when worming), stepping onto things. Learning how to release herself from pressure basically. She is naturally very resistant in high pressure situations so its all about asking her to think things through before reacting.
Start with simple back and forward, then ask for turn on the forehand. I expect her to do this perfectly now so if she doesnt for being too nervous about something I get her attention back by insisting on perfection as this demends her attention back on the task in hand, not on the bird flying out the tree or whatever. After turn on the forehand I might put her into a circle on the end of her 6ft rope (dont have anything between 6ft and 24ft lolz) and use body language to ask her to stop/walk/move arse out/move head out/stand perpendicular to me/ anything that pops into my head really. If she doesnt understand I break it down into smaller chunks.
I also ask her to walk over wierd stuff and raised things to keep her quite literally on her toes. Crates, feed bags, crappy rugs, sideways along poles, sideways along shavings bales. And I ask her to wak between things that physically put pressure on her like two jump stands, or under low branches. Its all about pressure, thinking it through, trusting me and doing it.
And lungeing and longrein stuff is of course ground work. I use lunging in a headcollar to encourage her to go off voice aids only, and work in a bridle to enforce pressure-release when she gets a little too eager, but also to encourage her to go off lighter bit pressure by responding to voice aids along side gentle bit pressure. Then theres work in the pessoa (new fav bit of kit!) which supples and strengthens her. All forms of lunging enforce my leadership and teach young horses how to balance themselves on different sized circles.
Longreins are good for teaching horses to go forwards into the unknown without the support of the handler next to them, and lead horses would drive the other horses from behind in the wild.
Ground work always enforces my leadership, trust, and teaches the horse there is always a better thing to do than panic and freak out!
We lose ourselves in the things we love, we find ourselves there too ~Kristen Martz