How do I handle lots of optional inputs in a form?

I have a form with 11 input fields - Some are dates, some are text, some are range sliders. 5 of the inputs are optional.

Tagging all five with the "Optional" text looks really clunky. Is there a better way to handle having lots of optional fields instead of spamming the "Optional" text?

It means that a user may leave 5 fields blank upon completion yet these 5 fields are taking up 50% of the space.