Life is too short to spend your precious time trying to convince the person who wants to live in gloom and doom otherwise.
There's no traffic jam on the extra mile.
Go as far as you can see and you will see further.
For every sale you miss because you're too enthusiastic, you will miss a hundred because you're not enthusiastic enough.
You have to feed your mind daily with the good, clean, pure, powerful and positive.
When you do more than you're paid for eventually you'll be paid for more than you do.