Almost everyone when we start something new we do it with great enthusiasm, like a courtship, the birth of a child, a marriage, the beginning of a career or a master's degree, the beginning of a new spiritual discipline; they have a great momentum at the beginning. But this is lost over time. How to keep it?
Personally I have worked on the spiritual path since my adolescence, and at the beginning I had a lot of momentum, but then I left it the same. Now I'm taking it back with great impetus.
And speaking of the subject, the book "Entusiasmo" by Gurumayi Chidvilasananda is a great teaching. It shows us that since we were born and created, it was because of a great energy and enthusiasm that she calls "the ecstasy of God". Then it teaches us who we really are and how we can wake up and realize that God is in our inner being.
Then it teaches us how to approach that God in all aspects, with the word, eliminating hatred (especially that which we have for ourselves), perseverance, patience, forgiveness, balance, envy, selfless work (Seva) and gratitude are some of the aspects that can help us to keep that enthusiasm in our approach to God.
The book is based on the Hindu philosophy. It is worth reading it, studying it and absorbing it in your heart.