The Bible says you'll reap what you sow (Galatians 6:7.) You should realize, however, that the return on investment will not necessarily be proportionate, in both positive and negative cases. In some cases the disproportionality will be staggering.
In the parable about the vineyard workers recruited at different points during the day, we see that the master paid them each the same, even though some had worked much longer than others (Matthew 20.) The reason for this was that he was pouring out unmerited kindness on all of them, according to his good will. In the parable of the mustard seed (Matthew 13,) we see that in the kingdom of God, the tiniest of investments (a sincere "yes" toward Jesus in your heart) will reap the largest of rewards (eternal life.)
On the other side of the coin, God is exceedingly merciful with negative consequences in this age. Consider a scenario where one of your children causes thousands of dollars in damage to someone else's home through an act of willful negligence. You as the parent have to make restitution for their act, and the strictly fair thing to do would be to force your child to work off every single dollar. The child would have to drop out of school. Instead, you impose your own discipline on them, designed for their good. You allow them to suffer part of the consequences by working an afternoon job for 3 months, and you take away some privileges. You still allow them to reap what they have sown, but you mitigate the consequence so as not to overwhelm them. Once again, it's not proportional. God is a good Father and often lets us suffer a portion of the consequences of our action such as sorrow, damaged relationships, lost money, etc., for the sake of loving discipline. He carefully handles each case with love.
It's important to realize that God is reserving the full, amazing, and fearful release of consequences and rewards until the day of judgment. He is so patient with people who are refusing to obey Him. He is giving them chance after chance after chance to turn away from their sins and follow Jesus. He allows them to experience just enough consequences and pain to wake them up to turn from their disobedience before it's too late. Sadly, there are some people for whom no warnings are sufficient to snap them back to the reality of the rotten fruits which grow from the seeds of sin they have sown. When Jesus returns at the end of the age, He will release the fullness of His wrath on those who do not know Him (Romans 2, Matthew 25, and Revelation 15-20.) If you don't know Him, NOW is the time to heed his gentle warnings. Pain in your life is His reminder that things are not right in the world or in your life, and everything won't be made right until He comes back.
The Gospel is not about God going back on His Word about reaping and sowing. He will never go back on His Word. It's about His lavish generosity in paying out extravagant dividends of life, righteousness, forgiveness, peace, joy, love and more in return for the tiniest investments of faith and obedience. Just imagine the multiplied rewards He will give you as you invest every moment, every relationship, and every resource you have into His kingdom by obeying His Word (read Matthew 19:29 and Luke 6:38.) Don't miss out on this unique, eternal investment opportunity. Tomorrow is not guaranteed.