The following is a thought process I put myself through when I was eighteen thinking about infinity and God:
Infinity is a complex concept to understand. You can think about a number and add one. Continually. But your brain will soon get tired. Running on a constant mathematical treadmill. But in reality all numbers already exist. There is no adding one because it is already there. In order.
So change tack and imagine your mind in space racing past Mars. Racing past the planets towards the smallest pinpricks of lights in the blackness. Unknown and unnamed. Continually pushing your mind forward. Only to grow tired realising that the stars will always be in front of you. Unknown and unnamed. Unreachable. And you come to the conclusion that the speed of travel is redundant. No speed could ever be fast enough to travel from here to infinity. In fact, you realise that time has become effectively zero when distance has become so large. Compare being able to travel to the edge of the Milky Way in the blink of an eye. Imagine in the next blink being able to have travelled further and so on. You end up with the same micro second covering all imaginable space.
Change tack again. To be effectively everywhere at the same time is the ultimate definition then of infinity. You realise that you must drop the law of physics of this world that ties distance and velocity. Distance and speed are holding you back from gaining knowledge of what an infinite thing could actually be like.
The thought should come that an infinite thing does not need to travel across itself. It just is. In much the same way you do not think about the space you take up. You just are. Imagine how that must feel: what it is like to be absolutely everywhere at exactly the same time. To take up that much space. Imagine what it must feel like to be truly omnipresent. But realise that you feel your existence as all entities must feel their existence. The two don’t overlap. You exist and God exists outside of you. And this world is a simile for how you exist in God. Realise then you must die and be non-existent for God to exist absolutely everywhere. For where you exist God does not. (Hence why we must invite God into our lives, the power of Let thy will be done etc. We must make a conscious effort to humble ourselves into nothingness and bring God into this world).
And this when I was struck with awe and realised that in comparison to the size of the universe and the infinite being of God I am truly nothing.