You can do this AFK. If you got a horse (catching or main story gives you a tier 5 horse at some point). Make a route around Heidel. And do this AFK.
Tips:
1. Get enough Carrot (if got 250 in inventory). And turn on automatic feed when needed.
2. To make a route around Heidel. Press on the map LT and square to make a route. (The route is markdled green).
3. Check if you dont get stuck during you auto run/training.
Enjoy