Singapore was my home for 3 years before I moved to Italy. It was there I fell in love with the tropics as the city is full of nature reserves and jungles. If you want to be in nature, surrounded by nothing but giant green trees and giant leaves bigger than an umbrella, you just choose one of the nature reserves close to you and within minutes you immediately forget you live in a city-country of 5.5 million people.
I lived right next to Singapore Botanic Gardens, where this picture was taken. It is such an incredible place! Every Sunday I taught yoga classes at one of the gazebos in the park. The greenness and the sounds of birds fill up the space, it is such a perfect setting for calming the nerves. If you want to have a yoga class there during your visit, just visit meetup.com where you will be able to find various scheduled yoga classes at the gardens (all in English).
Tourists barely visit the Gardens since it's a bit away from the busy CBD district, but I would put it at the top 5 on the itinerary. Once a month on Sundays at 6pm, there is a free concert in the Park at the beautiful amphitheater, surrounded by a small lake full of giant lilly pads. Maybe you are lucky and you visit Singapore on one of those days!
What did you like the most about Singapore? I'm curious to hear!!