import (
    "fmt"
    "time"
)

var now = time.Now()
var yesterday = now.Add(-24 * time.Hour)
var tomorrow = now.AddDate(0, 0, 1)
var nextMonth = now.AddDate(0, 1, 0)
var nextYear = now.AddDate(1, 0, 0)

fmt.Println("yesterday is", yesterday)
fmt.Println("tomorrow is", tomorrow)
fmt.Println("nextMonth is", nextMonth)
fmt.Println("nextYear is", nextYear)