Our world says, "Have all the fun you can! Live for the moment! Don't worry about the future!" But as you're discovering, time marches on, and before you know it the future has arrived and you are unprepared for it.
The Bible actually says much about our responsibility to work diligently and prepare for the future. The writer of Proverbs observed, "Lazy hands make a man poor, but diligent hands bring wealth" (Proverbs 10:4). The Bible also reminds us that even God's smallest creatures teach us to work hard and prepare for the future: "Go to the ant, you sluggard; consider its ways and be wise! ... It stores its provisions in summer and gathers its food at harvest" (Proverbs 6:6,8).
At the same time, the Bible also warns us not to worry unduly about money or let our lives be ruled by it. Instead, we are to trust God and find our security in Him. This is why Jesus said, "Do not worry about tomorrow" (Matthew 6:34).
Although you can't change the past, do all you can to prepare financially for the future. Most of all, make it your goal to prepare spiritually for the future, for one day this life will be over. Are you prepared for that day? You can be, by giving your life to Christ and trusting your future into His hands.