Many will come and try to convince you that obeying and keeping God's commands is legalism. They will tell you that you need not holy habits like prayer, keeping the Lord's day, communion, baptism, worship together with other believers, mortification of the flesh, the reading of God's Holy Word, singing His psalms in worship, and hearing the Word preached.
Keep your ears away from such, for they follow the desires of their sinful nature. They desire that which pleases their senses. They like little religion, and justify their sins by saying they are 'free'.
Legalism is trying to keep the law in order to earn salvation by your 'good works'. But remember, keeping God's commands and obeying them (battling the flesh to keep them even when our plans are disrupted), is not legalism. You are not working towards something you earn or deserve. Keeping them is love. Love towards the One who saved you. Towards the One who gave His precious blood as a payment for your soul.
He says: "If you love me, keep my commandments". It does not give us freedom to do as we please; but our pleasures are now to be transformed, mortified, purged and aligned to His will and His pleasures. We will desire that which He desires and enjoy what He enjoys.
It is a painful process, it is a cross to carry, it is a battle to fight, with a great reward. Carry it humbly seeing your own frailty. Carry it strong, as a soldier in the middle of the battle.
Like R. C. Sproul said: "Freedom is a precious commodity. But our freedom has limits. We are under restraints and we are accountable. We are ultimately answerable to God. We are simply not permitted to do everything we might want to do"
Be careful, be on your guard. Be diligent and work out your salvation with fear and trembling. Watch your heart and know it well. If there is in your daily work a sense of 'earning' God's favor, step back and remember how impossible it is for you to please Him on your own in the first place. It is finished. His work, His purchase, His acceptance, His victory. And now, looking at the cross, at His finished work, at the redeeming blood, you have nothing else to give but to obey because of love.