Mindset

How much of life is just about your mindset? Is it just about a person's attitude? I don't want to be fake or superficial. I'm a fairly realistic person but am I thinking too much about the glass being half empty?

It's pretty difficult to be positive and/or joyful when you are sleep deprived. But I'm thinking that sleep deprivation is more the norm than the exception with small changes. So the sleep deprivation is not going to be ending any time soon. So if it's not going anywhere, maybe it's time to alter the mindset?

Can you be realistic and still experience joy? Is it just a mindset?