Please choose the correct ending to complete the given sentence: Pets and Animals: [header] How to condition your horse for endurance riding [title] Assess how fit your horse actually is. [step] Does he start puffing when you take him up a short slope? [title] Once you have assessed your horse, slot him in at the relevant level. [title] Starting with the very unfit horse lunge them for 5-10 minutes each side every other day for a week, then increase to 10-15 minutes each side for another week.

Ending1: [title] Then re-elevate the horse for 3 days, until he begins to walk easy. [title] Make a habit out of taking your horse to the stable on occasions. Ending2: Be careful you aren't stressing your horse as lunging can be stressful for your horse's joints. [title] After two weeks start riding your horse-start slowly. Ending3: [step] When you customize this incremental lunge, do it more slowly. [title] If your horse is healthy enough for endurance riding, always leave it until the last minute. Ending4: [step] Remember to keep your horse still at this exercise. From now on, limit your journey to just lunging the horse after 45 minutes.

Answer format: ending1/ending2/ending3/ending4