I am not religious but I can see how it brings peace and purpose to so many who do.
I think waking up being thankful for the little joys in life; seeing beauty in most things or creating it; nurturing the bonds we have with people; being kind and thoughtful and being with people who genuinely care and love us and finding joy in the most basic things can turn the mundane into something special each day.
What helped shift my dark periods in life was to first identify what it was and then make that a goal to improve and work on.
So on my list has been my DH, clutter, untidiness, fitness, improving skill in a language and in a sport.
So instead of moaning about each and every one of my sources of unhappiness/ dissatisfaction ( which got me nowhere) I set about to do something about it.
Starting out with paying more attention to my DH and giving him daily massages. He reciprocates and our communication has also miraculously improved!
I have taken up sessions at the local leisure centre which started when I got a free pass from the GP after having been ill and not very mobile. Now 2 years later I am fitter than I have ever been in my life!
I have decluttered one drawer at a time as doing too much was too overwhelming ( I am naturally a hoarding/ untidy person) and I have actually been so proud to see cleanliness and space after so many years ( I am in my 50s so it has taken me 30 years to improve).
I think the secret to happiness and purpose in life is to be continually learning, improving, helping, loving, being kind, thoughtful, struggling on no matter what and being able to laugh and get joy from those closest especially, or with pets or flowers or being creative and being as active as you can possibly be and out in the fresh air, if possible.