Well-formed Goals: Should be obtainable, realistic, measurable, positive (presence of something instead of absence of something), concrete, time specific.

Examples:

Ashley wants to make a 90% on her next test in her social work class.

Example of poorly-formed goal:  Linda wants to win the lottery using her birthday numbers.

Good response:

That would be nice - then you can either go through and talk about if it is obtainable (but most people already know this is not realistic). Another question - what would be different if you won. - keep breaking it down.