Had We not made you firm, you might have leaned a little.
Steadiness is a gift from Allah
Ibn Kathir explains that Allah is the One who took care of His Prophet ﷺ and helped him, his Helper, Supporter and Protector. The verse shows that even steadiness comes from Allah. If the Prophet ﷺ was told this, how much more do we need it.
You feel proud that you did not give in this time. You stayed home from that party, you closed that tab. That strength was given to you. Thank Him for it, and ask Him again tomorrow.
I stay on track because I am disciplined.
Allah keeps me firm, so I thank Him and keep asking.
After your next prayer, ask Allah in your own words to keep your heart firm on His way.