I Had A Question About Masturbation. I Recently Noticed I

I had a question about masturbation. I recently noticed I cannot masturbate to completion. I was in a relationship but not anymore so I've been doing all the pleasure to myself. But I can't do it anymore. I can get hard. But I can't finish. I get tired and my dick gets soft. I take medication. I vape and sometimes smoke. You can say I'm pretty active. Been going to the gym. That's all the information I can think of giving you.