After you complete the stable in Lookout Landing, Lester asks you to help find his horse that ran away.
Quest Location
This quest is available from Lester in Lookout Landing after you finish the quest The Incomplete Stable, which you can do after you have defeated the boss in two temples.
Find Spot
Go out by the south exit of Lookout Landing, then go southwest. You are looking for a horse with a black mane and tail, with a beige (yellowish-grey) coat and grey spots. Click the button below to see a picture of Spot.
After you catch Spot, ride the horse back to Lookout Landing and talk to Lester while on horseback.
Quest Reward
Lester gives you 50 rupees, a Swift Carrot, and you get to keep Spot if you wish.