Let's build a short story for a second...
Jane and Joanne Doe are identical twins of average health, weight and fitness. They both decide to take up running but have to find someone to run with as they can't run with each other (they work different shift patterns, let's say)
Jane runs with Peter. Peter shows up at the same time every day and he loves to run, so he's always smiley. He makes polite conversation and offers Jane a lot of encouragment, especially when her knees are aching a little or she doesn't feel that she's improving. Peter has been running for longer than Jane, and plans their routes carefully, only increasing the distance and difficulty gradually. He encourages Jane to take part in a fun run, just for the hell of it. They both complete, in average time, and have a lot of fun. The day becomes a good memory for both of them.
In time, Peter is not just a running partner, he calls round for coffee and a chat too. Jane loves to run with Peter and the friendship is really good for both of them both physically and emotionally.
Joanne runs with Paul. Paul turns up when he feels like it, and sometimes he doesn't turn up at all. Joanne never knows quite what mood he'll be in. If he's had a bad day at the office he is rude and sullen and takes it out on Joanne. But if things are going well he wants to run much, much further, which Joanne finds quite difficult. Paul is critical of Joanne's efforts, and often says she puts no effort in, but she notices that he rarely criticises his own technique.
When Joanne picks up an injury from their inconsistent training, Paul says she is just making excuses, but a doctor confirms that she has damaged a tendon.
Joanne gradually loses faith in running as the relationship with her running partner becomes more and more unsatisfactory. Eventually she gives up, and finds through a mutual friend that Paul is running with a 'better' partner now.
When it comes to your horse, are you Peter or Paul?