The other thing is that the progress is relatively slow, people need time and space and trust to make movement, in my experience, it does not happen quickly at all. I found that somewhat of a challenge as well. HOWEVER, what I will say is that I use the training I got during my program in every aspect of my life, in my work, with my coworkers and my boss, with my clients, and in my personal life.
I could say that the difficulty of being a mental therapist is that every individual person is different, with differing personalities. Therefore, it would be your duty as a therapist to become intimate in learning what you can about the individual personally, making it more effective in administering your treatment and advice accordingly.
That is all the advice I can muster for you, Mylar. Hope this helps!
As far as a timeline, it depends on the degree area you want to pursue. There is a different timeline to becoming a licensed mental health therapist with a degree in psychology (PhD or PsyD), vs Social Work vs Marriage and Family Therapy vs Licensed Mental Health Therapy . You can looks those up to see how you want to spend your time and state requirements for licensure.