CNA Striving to be an RN in Mental Health

Hello. I am new to this forum and am currently a student in the RN program at my community college. I am in my first semester, and will be doing the CNA program. My ultimate goal is to work in Mental Health/Chemical Dependency as an RN, and I believe a good step to start would be a CNA. I was just wondering for those RN's working in Mental Health/Chemical Dependency, how did you do it? What route did you take and what are your reccomendations? I understand the job as a CNA can be challenging, but rewarding. Any information/opinions are appreciated! Thank-you.