Simulated training is done via the riding hall or the stables. There is a range of different routines to choose from, each affecting different stats. More difficult routines will yield more XP, but are also harder to finish. The higher stats the horse has in the relevant stats, the more difficult routines it can take on. The "Chance of success" bar gives an estimate of how likely it is to succeed.
The player can choose for how long the horse should be in training. Longer routines will yield more XP, but while the horse is in training, it cannot be used for anything else.
Upon finishing a routine, the horse will get a grade from A (best) to F (worst), depending on how it performed. The better grade, the more XP it will get. The grade scale from best to worse is the following: A, B, C, D, E, F.
All stats can be trained in simulated training, except Mentality. Mentality is trained through riding on trails.