Vit C helps, Phosphatidyl Serine (PS) just helps on top of that. I've been taking Invalid Link Removed for the past 3 months, and I definitely think it helped with preventing overtraining and boosted my immunity. I've decided to make it a staple, and can't wait to try the new version with the alpha-GPC for a GH boost.
Edit: There's plenty of good threads on Cortisol Lowering supplements that can be found via search and I don't want to beat a dead horse, but look into 7-OH DHEA, or if you like herbals Relora was mentioned, and you can stack it with an adaptogen like Rhodiola or Ashwagandha.
To get a good idea about how PS works, read Invalid Link Removed