If I put a 25 pound backpack on you and asked you to walk,trot and run across a field,what would happen to your balance?
Now let's put a 25 pound child that is kind of moving around a bit.
There is a difference between static weight and moving weight,but the moving weight is the hardiest to balance.
So your horse has to get his balance in a straight line first then a circle,in that order. You are trying to evenly load your horse.
Rating happens after balance is achieved.
A weight shift back and a touch of pressure on the bit as a cue and the horse should start to slow a bit.
You should have three speeds for each gear you are in.
Very slow walk,walk,fast walk.
Very slow trot(jog),trot,extended trot. Etc.
You are looking for very even foot falls in rhythm and as you walk back over your hoof marks then look to see that they are in line.
A lot of horses have a hard time running straight.
Running in a pasture is fine.