That is about 30,000 b a month. What is your desired lifestyle? You okay living like a semi bum in a lousy condo box far away from activities and conveniences? What are your hobbies, plans, etc.?
At your age a decent medical policy will cost around 5,000 b a month.
You want to travel around and eventually explore neighboring countries?
I assume you are male. You want female company from time to time?
The 30 k will not go far at all in Bangkok. I think 100,000 k a month is about right to enjoy a proper retirement lifestyle in Bangkok. So, invest your savings appropriately.
Good luck.