varying/ varied/ various/ a variety of

Varying his routine, he took a walk in the park.

Various books were strewn on the floor.

A variety of books were stacked on the table.

You should eat a more varied diet. No one can survive on only diet Coke and pizza.

Please consult this dictionary.

Varying is connected to changing or changing over time.
Varied is different or differing, options

So a varying diet is a diet that I change from time to time, maybe every few months I eat low carbs for a month.
A varied diet is a diet that has different kinds of foods groups.

'varying' - participle -> To be in the process of changing at the time referred to

"I am/was/will be varying the conditions of your employment"

and adjective "The varying quality of the light made photography difficult."

'varied' - past participle = of an item that has changed or has been changed in the past "I have varied the conditions of your employment"

'Varied' - Adjective: of an item that is represented in several forms as a result of change or being changed "The varied quality of the apples meant that they could not be sold."

'various' - adjective: of items in a random collection

'variety - noun = a random set of types of an item.