I think if you love yourself or have decent self esteem, when someone says they love you, you believe them. When someone says, hey you look nice, you don't dip your head and mumble something--instead you say thank you.
Most of all you feel a sense of contentment, you are up for improvement but you don't self-hate every time you make a mistake. And I think is is also manifested in how we care for ourselves, our bodies, our hygiene and how we present ourselves to the world. Do you want to be seen in dirty clothing or do you take the time to be clean and presentable and show the world that you care about yourself.
It is a multi-factored process.