I heard that when you hit something that is more or same level dense as your bone - you get bone damage -> something has to give in and it's softer material which is bone in this case... If you are not planning to fight professionally it's not worth it.
IMO the best way is to kick heavy bags - there are different heavy bags though - some are soft and some are hard, so make sure it's the hard ones. Kicking/checking is not so bad with shin guards on (make sure it's not super-protective ones).+ Do work on conditioning the thighs and body, so that you can take kicks less painfully without checking
HONESTA MORS TURPI VITA POTIOR