Training = breaking down the body
Recovery = building the body up a.k.a. getting stronger
So what you should take from this is this.  You are NOT getting stronger when you train.  You are merely breaking your body down in order to elicit a specific response.  That response being getting stronger/faster/cardiovascularly efficient/etc.  And that response is played out only during rest and recovery.  So think of it this way.  You are a bank account.  Training, stress, life, and illness are all withdrawals from that account.  Recovery being in the form of GOOD nutrition, sleep, mobility, ice baths, and massage are deposits.  So when you train, your account goes down.  Then when you eat right and sleep, your body recovers and a deposit is made.  The more strict you are with diet, lifestyle, and sleep the bigger those deposits will be, and then your bank account actually gets bigger over time.  So the point is this; don’t neglect the recovery aspect of training.  When dealing with training, more is not always better.  Listen to your  body and give it the recovery it needs.