You feel alert. It’s okay to feel tired every now and then. But it shouldn’t happen constantly. One of the signs that your immune system is strong is a sense of alertness and awareness throughout the day.
You sleep well. Not only should you be sleeping through the night, but you should also wake up feeling well-rested, rather than feeling like you could sleep for another few hours.
You don’t feel sick all the time. Once you get over one illness, another doesn’t follow in its place, followed by another, and another…
You regulate your emotions well. When you don’t feel well, even subconsciously, it can affect how you treat yourself and others. Being healthy means having more than just good physical health.