How often you should workout?
So this is a interesting questions, that many people ask and worry about it.
By my experience working with fitness for almost 10 years, what I see to give the best results for most of people is 3 resistance training a week mixed with 3 aerobic actives, splinted in 1 day training the day after cardio session for 6 days and 1 day of total rest than repeat on the next week. Usually the training and the cardio session you should aim for 45 to 1:10 no more than that, and less won't work efficiently. Is the perfect balance for people that are looking for a nice and well balanced body and healthy.
A well made workout routine divided by training ABC is key for nice results, and for the cardio if you can mix and match will be better also, for example during the week, 1 day of playing tennis, 1 hour of swimming, 1 hour of bicycle find something that you like and have passion to do, to become easier to stick with.