How to boost my immune system

I had a meeting with my boss today, to sort me coming back to work and also, my new 2 shifts a week idea. She had lots of ideas on how to boost my immune system, so I've been researching all afternoon and have no got a list of things I need to do:
Eat more fruit, veg and nuts (I'm not too bad at this already! Though need to buy nuts!)
Eat less sugar (This one is really going to hurt - my chocolate relationship of late has been very very bad!)
Meditate  (I already have a CD to try!)
Socialise more (hmmm... not sure about this yet, but will try to get out and see more people)
Walk dogs (I really like the sound of this and have looked up my local Dogs Trust Centre to contact)
Eat probiotic yoghuts (expensive, so might have to give this one a miss)
Get more vitamin D (nothing to say about this one really!)
Get garlic, echinaccea and ginseng supplements (I think will all these pills, I will rattle!!)
Start using Vitabiotics Immunace (hope to find them cheaply somewhere!)
and finally have more sex! (perfect, as we're still trying for baby no2!)

So there you have it! I think if I manage to do this whole list, if my immune system doesn't pick up then it must be totally broken!!