import (
    "fmt"
    "github.com/mcuadros/go-defaults"
    "time"
)

type ExampleBasic struct {
    Foo bool   `default:"true"` //<-- StructTag with a default key
    Bar string `default:"33"`
    Qux int8
    Dur time.Duration `default:"1m"`
}

func NewExampleBasic() *ExampleBasic {
    example := new(ExampleBasic)
    defaults.SetDefaults(example) //<-- This set the defaults values

    return example
}

...

test := NewExampleBasic()
fmt.Println(test.Foo) //Prints: true
fmt.Println(test.Bar) //Prints: 33
fmt.Println(test.Qux) //Prints:
fmt.Println(test.Dur) //Prints: 1m0s

example := ExampleBasic{
    Bar: 0,
}
defaults.SetDefaults(example)
fmt.Println(example.Bar) //Prints: 33 instead of 0 (which is zero value for int)

example.Bar = 0 // set needed zero value AFTER applying defaults
fmt.Println(example.Bar) //Prints: 0