I've been in therapy for about 17 years now. I started pretty young and I can honestly say I've made a lot of progress since then. I had a lot of unhealthy, self-destructive coping skills back then and it took a REALLY long time to work through my personal issues, but I've become a much stronger person because of it.
I'm on my third long-term therapist right now. The first one I had while I was a teenager until I was too old to see her and my previous therapist I had until I moved to another state. There were times when I didn't want to go, times where I fell apart, long periods of time where I was depressed. I struggled, but as years went on, the lows weren't as low as they were before.
My experience has been positive overall. It will be difficult at times, but know that's part of the healing process as well! Wishing you a great experience