There are many things that are good for the soul. I am an advocate for doing what makes your soul come alive. We might agree that traveling, spending time with friends, an art class, etc are good soul igniters but I want to add faith to the mix.
There have been many articles written in the past about faith and its correlation in making people better humans. Some call it the "science of belief". There is something that clicks in our souls when we have faith in something and many times (not all) it helps people do things they never would have attempted to do without said faith. Many times, it helps people have a better disposition in life because they have faith that what they see is not all there is to life.
I remember years ago, after the birth of my second son and the emotions my husband and I had about the entire ordeal of a premature birth (26 weeks), the subsequent operations (29 in total) and the hospital mishap that eventually would make my baby unable to live a normal life. We were both mad at God for a time. After all, we thought, if this is how you treat those who serve you, what's the benefit in that! One day, my husband had a conversation with a Rabbi who was also a patient of his and he asked my husband after a conversation they had, "how would you feel if you didn't believe in God?" My husband responded, "I wouldn't like it" to which the Rabbi said, "then continue to believe!"
We have both continued to believe and it was most certainly good for our souls. Not simply because it "felt good" to believe in a higher power but because it helped us make decisions and behave in certain ways that have proved to be very good for us and our family. In most cases, when you practice faith, you change and become a better person, you're joyful and thus, your soul is content.
When you practice faith, you stretch more in all areas.
When you practice faith, you work at reconciling relationships.
When you practice faith, you believe for the impossible and actually attempt it.
When you practice faith, you allow God to work in you so He can work through you.
When you practice faith, you become a more compassionate person.
When you practice faith, you are more forgiving.
When you practice faith, you try to make a difference in the world.
Granted, there are exceptions to the rule and not all people change for the better, if at all. I get that. But for the most part, having faith is good for the soul. So I simply suggest, you do all the things that make your soul come alive and if you haven't given faith in God a try, hook up with a faith-filled person and ask them, "tell me about your faith and your God!" I promise you, it will be good for your soul.