Hi Shige,
Welcome to ER community.
Sounds like in your mind, retirement is doable and you would like confirmation. Also, you would like to know some success stories to encourage you to make the leap.
So good thing you found this forum b/c it is full of personal experiences of FIRE -> check out the “Life after” section for post retirement updates. You will find threads detailing the emotional, physical, and psychological journeys of retirees spanning a wide age spectrum, including plenty in their 50’s. Many experiences starting from T+1 (The First Day of Retirement).
Also, this is a chatty group. Now that GME and COVID have been pretty much talked out... the more info you give and specific advice ?’s requested, the more response you’ll get. This forum is almost 20 years old, while the human experience remains constant. I encourage you to dive deep into the threads. You’ll learn a lot, and probably gain some new friends/acquaintances to take on your journey.