Running in circles, chasing her tail? OR running the fence line and killing a grass trail.
How old is she and how long has she been doing this?
The reason I ask, is for all I firmly believe you can teach an old dog new tricks, I do believe it takes longer to teach them.
With patience and distraction of toys and treats, is the best way to stop them from chasing their tail. A firm 'ah ah' and then a distraction and then a treat for different behavior.
As far as running a fence line. Don't let her in the fenced in area without you. Place some obstacles where you don't want her running to force her onto a different path. Find out what she is running after and try to remove that irritation. Of course if it is cars, and squirrels and so forth that is a problem, but you will have to distract her and praise her when she stops.
The others will chime in with much better advice. These are two things I have not be blessed with. Well......the tail chasing I have, but I think it is kind of comical, but MMM is not obsessive about it though.