5 yr old lab fetch problem!

Question

handshake   Hello.I am Rameez from India.I have a 5 yr old lab (female).she hasn't been trained all these years apart from a basic sit and hand shaking.would be fair to say she responds well to handshaking..but doesn't always seek to understand the sit command.she doesn't good with fetch the ball game too.whenever i throw..she runs..grabs it in mouth and starts chewing it.she doesn't let go the ball from her mouth.i would like you to suggest some basic commands that she needs to learn and the procedure that i should be following in order to understand what that means.plus leash walk problem.sometimes she doesn't listen and walk side by side...but sometimes she doesn't. please help.

Answer
If the dog is already an adult then usually they are set in their ways. Dogs are either food or toy motivated. Some may also be praise motivated. But I would not say that an adult dog would have much success being trained without the assistance of a professional.