Successful adaptation is rarely about dramatic transformation; it is an accumulation of small acts of participation. The expats who integrate well tend to do the same things: learn the language beyond survival phrases, say yes to invitations even when tired, join something structured like a sports club, class, or volunteer group, and get curious about why locals do things rather than just noting that they differ.
The predictable challenges are the honeymoon crash a few months in, when novelty fades and frustrations pile up, the slow burn of missing implicit jokes and references, and the difficulty of moving friendships past acquaintance, since locals already have full social lives.
Two mistakes to avoid: retreating entirely into an expat bubble, which keeps you a permanent tourist, and forcing total assimilation while suppressing your own identity, which burns people out. The stable end state for most happy long term expats is a blend, keeping what matters from home while genuinely adopting local ways.