Start with lunging when you want to improve strength and endurance. Player experience recommends it early, including for young horses that cannot yet be ridden. Check the horse's information after training to see what changed.
Track both stats
Note the horse's starting strength and endurance, then compare them after a session. A player training walkthrough describes strength as the reserve used for demanding work and endurance as a factor in recovering that reserve during a ride.
Choose the next session by results
Look at current stats alongside the horse's potential. If progress stalls, check whether the horse is approaching its potential before you repeat the same routine. Use that information to decide which horse to prepare for a harder event.
Spend strength deliberately
Watch the strength bar when riding and leave enough for demanding sections. The official Steam description links training to competition qualification. Build the horse up in practice so the next class suits its current ability.
FAQ
What is a useful early exercise?
Player experience recommends lunging for both strength and endurance.
How can I tell if a session helped?
Compare the horse's current stats before and after the session.
Why is endurance useful on a longer course?
A player walkthrough describes it as helping the horse recover strength during a ride.