As Trusylver suggests, 30 mins is fine. I have to admit to preferring 45 mins to a max of 60 mins for cardio on cardio days; since 45 is between the 2 I tend to opt for that one more, and I figure that all those 15 minutes extra all add up without me even realising it
Strength and cardio done in combo, such as every other day doing weights and then on the days in between doing cardio, will help to change body composition as well which means you'll look slimmer quicker. It's all good
