How do you honor/celebrate your loved ones on their birthdays?

My friend died 6 years ago when we were in college and his birthday is this weekend. All of our mutual friends live in other states now and none of my family or friends in my city ever met him.

I never know what to do for his birthday, I usually just end up isolating and feeling sad and restless like I should be doing something more to honor him. He was a really carefree and funny person and I think he would hate it if I spend the day sad.

What have you done to celebrate your loved ones on their birthday?