For general fitness, 60 minutes of moderate physical activity daily is important. This is to simply keep your blood flowing through your body and reduce your risk of many physical problems. However if you want to reach a specific goal you may need to add on to this.
Physical activity can be as simple as walking or as complex as high intensity interval training. Research as well as experience can help you decide one what you like to do and how often you want to do it. There is a general principle used in the fitness industry called the "F.I.T.T.E." (FIGHT) principle. You can adjust your physical activity based on Frequency, Intensity, Time, Type and Enjoyment. I like to start from the back of the list. Find something you enjoy. Then figure out what type of equipment you will need for this. Then you can find out the time it takes you to enjoy this activity by experiencing it. You might find out you like to do a certain activity at a moderate level but if it gets too intense you don't enjoy it anymore. So, you will then know your intensity and you can base your frequency off of your intensity. A more intense activity needs less frequency and a less intense activity might require more frequency to reach your personal goal.