I give all new members one piece of advice and it's this,"Don't look at good health or weight loss with an all or nothing mentality". If the only healthy thing you did for yourself today was drink 8 glasses of water, that's still a step in the right direction.
You will NOT derail any of your efforts at good health or weight loss because you haven't been able to exercise. Part of having a healthy lifestyle is also knowing when it's time to rest and recover from an illness.
So, don't beat yourself up because you're not perfect. You don't have to be perfect to be healthy.
Think progress, not perfection.