can one define postive mental attitude
This is an opinion question, I am assuming. What do you think? If you still need help developing your ideas, just ask.
This is as good a definition as any.
My definition is -if you use your head to make the best decision possible, use your hands to do the best job possible, then usually things work for the best. If it doesn't work, then you have learned something you didn't know.
Making use of all the resources available to you, a positive mental attitude is having confidence in taking the necessary steps to reach your goals.
Possibly a negative example might be helpful.
This might also be helpful:
Saying, "I can't do it." becomes a self-fulfilling prophecy, assuring your failure. Although a positve attitude does not assure that you will succeed, it makes it much more possible.
I hope this helps a little more. Thanks for asking.