What happens if I start the sale process and then lose interest halfway through?

What happens depends heavily on how far "halfway through" actually is. Early on, before a letter of intent or with only informal discussions underway, stepping back generally has little legal consequence, though it can affect your reputation with that buyer or broker if others hear about it. Once you've signed a letter of intent, specific provisions within it, particularly confidentiality and any exclusivity commitment, typically remain binding even though the price and most terms usually aren't, so losing interest doesn't automatically free you from everything you've agreed to.

The nuance many owners miss is the cost already sunk by the point they lose interest — a buyer may have spent real money on due diligence, accountants, and lawyers by the time you're deep into the process, and while that alone doesn't usually create a legal obligation for you to continue, it can shape how the conversation about stopping goes, and whether the buyer pushes back or tries to negotiate different terms to keep you engaged.

Before stepping away, it's worth having a business lawyer confirm exactly what you've signed and what obligations, if any, survive your decision to stop, so you can exit the process cleanly rather than leaving loose ends.