You are going to have to take the time to walk her down, armed with the halter and a stout lead rope. Keep your energy low and don't look at her as you enter the field. You will circle around behind her about 30' back, still not looking at her, at least no eye contact. Get her to move by using the least amount of energy that will move her. Start as tho shooing chickens. The goal isn't to get her to run off, just move her feet, even a few steps. BTW don't hide the halter, carry it in your left hand or elbow in plain sight. Continue to do this until she will try to protect her hiney and watch you with both eyes. It will become more difficult for you to get behind her and that's what you want. When she's facing you with both eyes, stand still, slump your shoulders and look at her knees or muzzle, just not her eyes. Extend your right hand, fingers downward and see if she will approach and touch your hand. If not, step back a few steps. A horse will often follow what is moving away. If she greets your hand, toss the rope over her neck and pull it off a few times. Put it on again then halter her. Do it up, then remove it and walk away. Leave her alone for a few minutes. She will either follow you or return to graze (or just stand there). Approach her as tho to circle. Just do as before only this time when she's haltered, groom her with your hands and pick up her feet. Then let her go and leave. You have made no demands on her. And to her, being haltered didn't result in work. Do the circling each time you enter the field. If you devote two or three days to this it will make a huge difference in the long run.She presently equates being haltered with work and the pasture space has allowed her to voice her opinion.