Of course we should try to be better, but not to try to please God. God is already pleased with all His people. He’s smiling at you right now. We should try to be better, because that is the right thing to do, for all humans.
Being “better” is not limited to Christians. Most religions teach that we should work hard to be better. Followers of Christ are the only people told that they CAN NOT be good enough.
This does not mean that we (as Christians) should not try to be better, but quit trying to be better to please God. Trying to please God will only cause you frustration, because you will eventually fail. You will ALWAYS fail eventually, this causes guilt, which causes frustration, and leads to a break down in our relationship with God, not originating with Him, but we will stop talking to Him, because we feel guilty.
So when I say, “stop trying so hard to be good” this does not mean, “go and sin in happiness”. Go and live your life knowing your are going to mess up, and knowing it’s okay, because God is not mad at you.