Weight loss problem.. help!!!?

just 3 months back, i used to weigh 165 pounds and it was allways disappointing to stand on a weighing machine seeing that the needle hardly moves towards the lower side.. my height is 167cm and my ideal weight should be 137 pounds around. so i was 28 pounds over weight. then just 3 months i decided to take the initiative of losing it rather than just thinking and staring at the weighing machine. i worked 2 hrs a day in the gym for 4 days a week. i stopped junk and controlled my appetite to an extent where i was eating 60% of what i actually ate before the 3 months. i did not see any marked improvement in the first month, i came up to 159 pounds. now i just had two months and i knew i wont be able to workout more than a month because i had my exams. i worked like anything and then during my exams i took right amount of healthy food. today i weigh 148 pounds after 3 months exactly. i am happy with this. what do you think about this? now my exams are over and i am lazy enough to hit the gym again because the climate is really cold, but my dad recently bought me a treadmill. i used to do a lot of cardiovascular in my gym which included 30 minutes of treadmill too. now i want to lose the extra weight. is it possible to lose it only through treadmill? how long will it take? how should i do it? please help......