Yes, all manifestation is impermanent. But I/consciousness is not. 
~~~ As long as we remain at the body mind level, we overlook awareness/consciousness which is transparent and the reality of our experience. 
It is not sufficient to live in presence. We also need to contemplate the reality of our experience and this way we realize that which is eternal. 
The eternity and infinity of I/awareness is an important realization. 
It is not possible to in-joy and be-joy as long as we remain at the level of impermanence. 
Love 💗