Keep initial fetch sessions low-key, rewarding and fun rather than rigorous training.

Tug toys, balls and soft squeaky toys often work best to spark natural chase and retrieve drives.  

Use treats and praise to mark and reward even picking up the toy at first to reinforce the behavior.  

Attach a "Get it!" cue when you throw the toy so they learn to fetch on command vs randomly.

Gradually step back further from the dropped toy location before cueing to return and build drive.   

Practice with multiple toy types so they don't only fetch preferred toys.

If your dog gets the toy but refuses to bring it back, move closer and use high-value treats to motivate toy release.