In the human experience we are programmed to think of our glass as either half full or half empty. From that state you are in lack and either doing all you can to keep what you have or trying to get more of what you believe you don't have.
One who always sees their glass as always full, regardless of appearances, knows his identity as Infinite Self.
Nothing can be added to or taken away from the infinite.
In practical terms,
When you know your love is infinite, it doesn't matter how much love you give or receive, you are always full of love.
When you know your happiness is infinite, it doesn't matter whether things are going your way or not, you are always happy.
When you know your energy is infinite, it doesn't matter how much energy you expend, you are always full of energy.
I believe lack and limitations are the effects of forgetting one's identity as Infinite Self. In other words, it is seeing the world from a half-full or half-empty perspective. Instead of trying to fix the effects, simply be still and remember that your glass is always full and your Infinite Self will take care of the details.
My glass is always full.