We are constantly becoming. Inside each new day, we are changing and evolving. Physically, mentally, emotionally, and spiritually, if we allow ourselves, we change all the time. That being said, however, why does that happen? Why are we not static beings? Also, how does it happen? Can we stop it? I suspect we can't, but the mind is a powerful thing capable of leading us to believe anything -- especially if we are motivated (e.g. by fear, by instinct, by others, etc.).
A tipping point is a sensitive, delicate place. In most cases, I believe it is a place where change/evolution begins/ends.