Does anyone have advice for some exercises I can do to keep my horse from leaning on the bit? She's a green broke BLM mustang and constantly rein roots and I feel like she's almost pulling me forward, especially at the trot. She's also very bendy. I haven't had a horse this green in years, and I've never had one that's quite as bendy as she is. I've watched some good dressage videos on YouTube, but I thought I'd try getting a few more ideas from you all. TIA!

From what I've seen, this is relatively common in green horses.

1. Make sure they move away from pressure - first on the ground, then move away from you with light pressure, than with just body language

2. Once they are 100% on it on the ground, do the same thing in the saddle. I start by flexing each way until they are light as a feather. Once this is accomplished, work on moving up in speed. Same with moving shoulders and hips, then ribs.

3. Do NOT let them pull you. Keep your hands firm and your balance correct, when they give up pushing, they will create their own releif. I like to exaggerate/quicken it up by using a heavy snaffle and giving to their release as well. Your hands are probably the most important part IMO when it comes to softening them up. Once I feel like they understand the basics, I will BRIEFLY move them into a square snaffle or a twist, however, these can do more harm than good if you aren't using them properly. The thing I like about a square is, when your hands are gentle, then they push, it bites them immediately if you are firm. If you are not gentle gentle with your hands, you can harden their mouth up super quick or do damage if you are too hard with it. When I say breifly - it generally only take a few rides - like 3-5 for them to get the idea, then I switch them right back into a smooth snaffle.

4. Lots of circles and direction changes to get them using their brain

5. Don't trot until she quits at a walk :) don't lope til she quits a trot

6. And as always - quit when you're ahead for the day!

Hope this helps!

German martingale. 

In my honest opinion, stay off their face when you ride and LESS DRILLS. Doing the same thing over and over and over is boring for a horse. 

Ditto

One-reined stops done correctly. I rode with Phil Haugen at one of his clinics and my horses have never been this soft and broke before.

You are very likely pulling too much with not enough forward motion, that puts the "root" on them in a hot minute. Pitch her some slack and get those feet moving. If she tries to run off, one rein stop her. Once you get her moving forward if she attempts to root pick up one side of the mouth or other and go that direction. Don't pick up with two hands until she knows to move her butt forward.