There is pleasant running along the Singapore River. It’s possible to go about 3.8 miles one-way from the Parliament area in the downtown core, heading west toward the Queenstown Stadium. Of course, you can shorten the run by starting near where you are staying, or turning around at some point. There are pedestrian ways along both sides of the river, in most sections. Then better initial section is on the northern side, then cross the pedestrian bridge to head to the southern side at the 1.7 mile mark. The path turns into the Alexandra Canal Linear Park, which is a very pleasant path. Bonus: Well lit at night.