It cannot be disputed that works are an integral part of the Christian faith. Though we do not work for salvation, we must work nonetheless. This leads many Christians to ask "am I doing enough?" I pray, but am I praying enough? I read the Bible, am I reading enough? I give to charity, am I giving enough?
These things are all good things, and we should never be discouraged from doing them. If someone asks me "hey, should I pray a bit more?", I'm not going to say "no, bad idea". But if someone says "hey, I only read one chapter yesterday... And it was Psalm 117...", I'm not going to say "well, enjoy Hellfire".
As Christians, all the work has ultimately been done for us. As God tells us through Paul, "...by grace you have been saved through faith, and that not of yourselves; it is the gift of God, not of works, lest anyone should boast. For we are His workmanship, created in Christ Jesus for good works, which God prepared beforehand that we should walk in them." (Ephesians 2:8-10).
So, question number 1: Do you believe? If you don't believe, you can do all the good works you want, God will never accept you. Without faith, it is impossible to please Him (Hebrews 11:6). "But to him who does not work but believes on Him who justifies the ungodly, his faith is accounted for righteousness," (Romans 4:5). So do you believe on Him who justifies the ungodly? If so, you're already "doing" enough. You're saved, you have an everlasting relationship with your Creator, and He will reward whatever good you do for Him.
Of course, the qualifier there is for Him. He's not going to reward any good you do for yourself. This is the mistake the Pharisees made. Whenever they gave to the poor, they blew trumpets to let everyone know. Thus, Jesus says "they have their reward" (Matthew 6:2-16).
But what are you doing behind closed doors? This is where the true measure of faith is. An actor is a different man on and off camera. Who are you "off camera"? Are you a Christian when no one can see you? If so, fantastic! God has begun His work on you, and I promise, He will finish it (Philippians 1:6). You will, in the flesh, go through seasons of self doubt, and I dare say for good reason: You aren't good enough. You didn't become Jesus when you converted, and the whole reason you need Jesus to save you is because you weren't Jesus before either. But when God saved you, He gave you good works to... walk in (Ephesians 2:10).
So really, there is no "enough". It's not a quantifiable thing. Thus, the question isn't "am I doing enough?", but "am I doing it for real?" When you pray, sure, you could maybe do it for a little longer. While you're thanking God for a meal, maybe you could take an extra 10 seconds to pray your neighbor enjoys one too. When you're reading Scripture, you could always turn another page. When you give to charity, I'm sure you could afford to give another penny. But God isn't keeping score like that. What He wants to know is whether you're genuine. And if you are, you may as well say "yes, I am doing enough".