I was on exit permit disruption through my supposedly reservist days. When I occasionally came back to Singapore, I sure call CMPB up to book IPPT, though not compulsory anymore since I was on disruption without unit. They thought I was very on, but I went there for the S$400 only! Later, they banned me!
It's very simple. Everyday you wake up, before going for shit, pee, brush teeth, wash face etc., do 50 push-ups and 50 sit-ups. Once a week go jogging (about 5 k.m. at any pace comfortable) and swimming (20 laps x 50 m. at any speed and style comfortable). When it comes to IPPT, just 5 stations give it all you've got if you want the money, silver S$200 is easy, most likely gold. At least sure pass, failing any station is impossible.
Swimming has nothing to do with IPPT but it builds up lots of stamina and flexibility that are very helpful in IPPT stations. Failing IPPT and going RT is crap. I have friends who lost jobs because always going RT.