Never regret a day in your life: good days give happiness, bad days give experience, worst days give lessons, and best days give memories.
You can't always control your days but you can control your response to what's thrown at you. Make the best of today by responding in a positive way to whatever comes your way. Look to God for guidance in your response and you can't go wrong.
This is the day that the Lord has made; let us rejoice and be glad in it.