Harder to get there during "me" time

I'm gonna come super clean here and say I masterbate a lot... recently I've found that it's incredibly hard to climax like I used to. It feels good but it takes so much longer and doesn't feel the same during it. I almost want to stop because I don't feel like it's worth it. I just get so tired out because it takes so long. I know my sweet spots and I'm doing everything I've done before that's worked to get there.. but I don't know what's up. I almost just want to give up, but a girl has gotta get rid of some tension sometimes lol. Anyone else ever had this happen?