As stated by others, no way in hell can you lose 40lbs in 1.5 months. That would require a daily caloric deficit of over 3,000 calories (takes 3,500 to lose a pound of fat). To put this in perspective; assume your bmr is 2200 kcal per day. You would have to eat nothing and jog about an hour per day OR eat normally and jog/bike about four hours per day to lose that much weight that fast. Pretty much impossible.
That said: don't get discouraged. You can lose the weight, you just have to accept the fact that it cannot happen quickly. One to two pounds per week is considered safe and also much more likely to stay off in the long term.
1. Assess your eating habits and try to cut out extra calories. This is a very individual thing. In my case it meant essentially giving up beer. Cut down on fried food, cheese, or whatever else adds the most calories. Don't starve yourself, just make sure you're not eating so much that you're undoing all the calories burned working out.
2. Start working out. Lift weights, run, walk, bike, swim, beat off, whatever. Just pick something you find somewhat fun so it's not a chore. Others to work out with makes the time go a LOT faster as well. Start small....say 1/2 hour of cardio 3-5 times per week along with some light general weights at the gym (nautilus is a good place to get started with this before moving on to free weights). Don't increase your total weekly volume of exercise (in minutes) by more than 10% per week to avoid injury. Some people like to keep an exercise journal as it gives you a concrete record of your progress in weight lost and how much exercise you're not capable of.
3. Rest. Proper recovery is the key to making progress. Work hard at the gym and then make sure you eat good stuff afterward and get plenty of sleep. Progress is actually made during recovery as this is when your body "rebuilds" and overcompensates for all the hard work you put in at the gym.
That's really about it, there's no trick or secret to it. Aim for a daily caloric deficit of 500-750 kcal or so and you will lose weight. Good luck. 🙂