Because Adam and Eve disobeyed God, they were caused to suffer and experience death on this earth. Read the Book of Genesis.
This is the fundamental characteristic of God.
God is God who punishes believers for every sin that they commit on this earth.
Bible is very clear on this point.
Book of Exodus clearly shows this essential character of God that is same yesterday, today, and tomorrow. God is God who punishes believers who sin ON THIS EARTH!
When Israelites (who had been delivered from the bondage in Egypt!) sinned against God, God punished them on this earth!
This is who God is.
Thus, you can be absolutely positive that for every sin that you commit, you will be punished on this earth.
How will God punish you?
(1) Physical Suffering, such as illness, disease, heart attack, stroke, cancer, etc.
(2) Emotional Suffering, such as depression, mood swings, memories that bring you pain all of sudden, etc.
(3) Mental Suffering, such as mental illness, deprivation of mental abilities, memory loss, dementia, Alzheimer’s Disease, etc.
(4) Accidents, such as car accidents, falling down the stairs, falling from bed, etc.
(5) Death of loved ones, such as God taking your child way before her time, because of your sins. Sins of the fathers shall visit the children, as the Good Book states.
God’s Word is clear that God is God who punishes believers for EVERY sin that they commit. You will suffer for every sin you commit, even if God will allow you to go to Heaven because of your repentance.
Every illness should be treated seriously as an Act of God to chastise you for your sin and bring you to repentance.