This depends on several factors. You should allow 24 hours between work outs or work on different muscle groups if you train on consecutive days. For example upper body exercise one day and lower body exercise the next. Cardiovascular can be done every day.

The truth is you can get excellent results by sticking a two or three days per week training. The more often you train the quicker your muscles will change but also you risk the likely hood that you will burn yourself out and stop altogether.

Incorporate exercise and increased activity into your lifestyle and your results will be more consistant