This is not an easy question to answer. Best put – you should be used to regular moderate to strenuous exercise on a weekly basis. Having said that, there are people who seem to be blessed with an innate ability to handle strenuous activities without exercising on a ongoing basis. Perhaps if you are one of those people you can ignore all of this article!
All the routes up Table Mountain are steep and stepped. The only exception is the jeep track from Constantia Nek, however this doesn’t take you to the top. Its still another 3-4 hours of hiking to get to the cable way and another 300 meters of uphill.
So if you wish to enjoy your hike you need good aerobic fitness and strong legs. Remember you may have to hike down also if the cable way is closed. Get going in advance and prepare as well as you can by doing uphill walks, time on your legs (up to 2-3 hours) and if you are a gym goer get advice from a trainer.
Being in good shape will make your hike a lot more enjoyable and you will still have the same sense of satisfaction.