exercising advice? Help

DavidG789

So I weigh about 109-108kg and started at 115kg about 3 months ago. So I've lost about 6-7kg now out of pure dieting and not really doing much exercise at all but my question is if I start going to the gym lets say 3 times a week how fast will that speed up my process? My Aim is to lose about another 28 kilos or so and reach 80kg by I want to say August but I think that's being a little too optimistic. Any advice? I was going to sign up this week and start doing about 30-45 mins of cardio 3/4 times a week e.g treadmill, rowing, bicycle, swimming whatever and see how that goes for me. I'm 19 and male btw if that makes any difference.