Helix Syn V Questions

I am a 23 yo and have an Aneros helix Syn V. It’s really comfortable but I feel like I’m not close to a super o. I feel that the first 20-30 minutes of my session are the best as I definitely feel pleasure but after that the feelings subside and I eventually end my sessions since I lose interest. I was looking for suggestions as many people can have a session for a few hours and really want to reach the super o.