when to shard your database

hey folks, ive been thinkin a lot abt database scaling lately. weve hit a point where read/write loads are gettin pretty heavy on our main tables, and im startin to wonder abt sharding. it seems like a powerful technique, but also a complex one to implement and manage. what r ur experiences? at what point did u decide sharding was the right move for ur app, and what were the biggest challenges u faced