A few things to check:

- Horses must be boarded to work in their career

- Have model horse career selected

- 'Career' checkbox above where you chooses their discipline career must be checked or they dont show in the list.

- Horse must have enough energy (20%) to do the work.

- Horses must be fed/watered (though they'll show up the list and say that the horse is 'thirsty', etc)

@SweetClover

My understanding is that people visit your profile and just look at your horse? But I'm also very unsure about this.

@Laycee - Model horse is a career for your horse to work if they are not a good showing prospect. Putting horses in careers (they can 'work' in a career 5x per day - or 20% of energy each time they work) is a good way to get a steady stream of money as the horse brings in a set amount of money each time they complete their career - which takes 30mins a session.

The amount of money goes up as the horse progresses through the career, starting at beginner, then novice, then amateur, etc etc.  Each level provides a set amount of money and points.  

The 'point' to careers is so your horses who may not be the best show prospects (low points, not great conformation) can still receive a steady amount of point increase over its life.  

There are multiple careers because if you look here you can see that training your horse in a career can give you certain stats. The model horse career gives:

So training a horse in the model horse will raise those stats.  Maybe helpful if you're raising horses for... dressage (flexibility, intelligence, power) but the training would be non-effective for a flat racing horse (speed, power, endurance).  That's why there are more career types available with premium - the stats change with the career.

But don't let the stats confuse you too much!  I train all my horses in their set discpline (flat running for tbs, trail for mustangs, cutting for american paint horses, etc) so they receive the points that will best for that discipline - but they might be a non-showing, career only horse due to bad conformation or show performance.

In Short! Horses that don't do well in shows, either because their non-performance stats (the stats they don't use for a discipline) or conformation (a horse with too many fairs or poors) should be put to a career so they don't lose you money from paying entry fees to a show they won't place in.  The career will earn them points and you money, and you can train them in the discipline you want so that they're still a good breeding prospect down the line stat-wise.

Note: performance stats are also supposed to have a weight to careers (so that they'll do better in certain ones) and how much a horse can make, but at my early stages of learning all this I haven't noticed any significant changes in my income between horses of the same career level.

@Nittrous

Thank you for your detailed explanation! I think that will help me