1.  Get Out and GO

The Good News: Walk for 30 minutes . . . regularly.  You increase the “killer cells” (like white blood cells) that go after bacteria that invade your body after just 30 minutes.

The Caveat:  3 hours later the effect wears off. This means you can’t go out and exercise a lot, then spend days sitting around.

Moderate aerobic exercise seems to be most effective.  Brisk walking, cycling, easy running or other moderate aerobic exercise is best (weightlifting may also work, but the results are not in yet).

 Do not overdo it. 75 minutes of intense exercise increases stress hormones, which are not good for the immune system.

 Do not wait until you are ill. Exercise gets your immune system tuned up and ready, but if you wait to exercise until you are sick, research suggests you could make yourself worse. When you get sick it is time to rest.

2.  Lay Around

No Caveat: Sleep 7 to 8 hours a night . Good sleep is critical for the immune system. Enough said . . .

http://time.com/5482827/how-to-boost-your-immune-system/