Back to triathalon training after a bad cold or flu

I’m starting to ramp up my base training for my triathalon season.  Unfortunately I’ve been battling cold/flu bugs throughout the fall/winter season.  My latest illness hit me 2 weeks ago.   Since then, I’ve been able to get back at it and ramp up my base layer of training.  My trainingpeaks metrics show I’m back up to a  CTL (fitness) of 67.  This is back to my level prior to catching the flu.  I’m approaching my training  slow and steady as I know that the training season is long and I need to be patient.

After a visit to my family doctor and reading up on cold prevention, I realized that I was short on Vitamin D.  I also realized, that I haven’t been taking any of my multivitamins.  A quick visit to the pharmacy was needed to stock up.  Vitamin D is especially important this time of year, where daylight is at it’s shortest.  A friend mentioned that his doctor advised him to get liquid Vitamin D, I assume for easier absorption.  

With a balanced diet, rest and vitamins, I’m hoping these are the ingredients I need to get back on track.