4 hr indoor session doubles and singles

I think I'm playing way too much tennis and I think it's becoming bit unhealthy at times and also like any other type of addiction I can't seem to stop... I think it stems from the fact that more you play the better you will get... and that's partially true for me but since I'm not professional and weren't bred to be one... I think it's doing more harm then good when playing too much.. I know pros that's there job and playing 4-8 hours a day is normal and I used to think how cool and fun it would be too be like that and get good.. Problem is it does the opposite... performance gets down, body fatigue, stress, and work progress dwindles..... I still think it's better addiction then illegal drugs, alcohol etc.. but seems though there's lot similarities