Reddit reviews Effective Biblical Counseling: A Model for Helping Caring Christians Become Capable Counselors

I'm not sure what books are suitable for Christians improving their own mental health.

At one time, I was interested in becoming a Christian counselor. Two of the popular books in that field are "Christian Counseling" by Gary Collins, and "Effective Biblical Counseling" by Larry Crabb. Your own pastor might have copies of those books or know where to get them. Some of the chapters in those books may address the topics that interest you.

On the subject of integrating psychology with spirituality, these two books on Amazon look interesting (but I haven't read them myself, so I can't vouch for their contents):

• "Psychology, Theology and Spirituality in Christian Counseling"
  
  
• "Psychology & Christianity: Five Views"