Grad couple 41 & 43. Annual combined $200k. Not too little but far from those super-earners here...

Been lucky with properties in the last 7 years...
1997: Bought first resale HDB 4-room at $385k
2002: Sold at $260k coz relocated overseas for work but returned sgp in 2007
2007: Bought first condo from developer at $700k+
2008: Sold condo for $900k+ (before TOP)
2008: Bought first landed inter-terrace at $1.08m
2010: Sold at $1.48m
2010: Bought next inter-terrace at $1.5m
2014: Still staying in it; current valuation $2.4m

Plan to continue working as long as possible.

Any advice for retirement planning?