Meaning of the word "habit is second nature" in English

What does "habit is second nature" mean in English? Explore the meaning, pronunciation, and specific usage of this word with Lingoland.

habit is second nature

US /ˈhæb.ɪt ɪz ˈsek.ənd ˈneɪ.tʃɚ/
UK /ˈhæb.ɪt ɪz ˈsek.ənd ˈneɪ.tʃə/
"habit is second nature" picture

Idiom

a behavior that has been practiced for so long that it seems natural or instinctive

Example:
I don't even think about locking the door anymore; habit is second nature.
After years of early shifts, waking up at 5 AM for him is a case where habit is second nature.