I used to get sick alot more but that was when I was partying and "kissing" all the girls. Alcohol and what not stunts the immune system plus intimate proximity, it's gonna happen. The trade off was worth it at the time. Still though whenever it happens it's usually not too bad for me. Kick it for a couple days, down some NyQuil or whatever's appropriate, and bounce back. I've had two times I was really ungodly sick. Once when I was 7. Super bad flu like bug that they never figured out. Almost died. Had nearly no muscle mass left. Couldn't even stand up for 2 weeks. Other was food poisoning from some bad pork. Felt like I was constantly being stabbed in the stomach with a twisting blade. And I fucking WORKED through it. Circumstances made it so.