The first thing that is affected is our ability to gain knowledge. Knowledge is a light, which Allah casts into the hearts of his believing slaves.
Another thing that is affected is our provisions. We will not leave this world until we have been given everything that is written for us. The Prophet (pbuh) encouraged us to have taqwa of Allah and trust that Allah will give you everything you need.
The third thing is you will feel a distance with Allah. You will not feel comfort from prayers or listening to the Quran. Think what has distanced you from Allah so much? May Allah protect us.