Actually this is so wrong it's borderline idiotic.
There is no way you can offset a bad diet with exercise alone.
While playing a sport you like 3 times a week is a good solution you need to play that game/sport for a minimum of one hour (1.5 hour really) and intensely enough to keep your heart rate up - basically work up a solid sweat.
But even that will burn no way near enough calories for you to lose weight if you are not eating right.
So yes losing weight is easy: Count your calories. Cancel sugar out of your diet. Exercise regularly and with intensity.
The discipline to do the above your whole life is hard - that's why so many fail.