I think it would all depend on what you are doing at the gym. Cardio is always the best in order to shed pounds but don't push it. It won't happen very quick. And just do weights in order to maintain instead of gain muscle. Remember muscle weighs more than fat. Also you are 32...once you hit your 30's your metabolism completely changes and slows so keep that in mind too.
Hello!
You very well can understand that staying in shape and being athletic cannot be achieved in a single day or should not be taken as a short term goal.
Proper diet, proper regular exercise should be part of your daily lifestyle to stay in proper desirable shape you want.
I would suggest you to take a realistic goal of 2-3 months for the 12-15 pounds and go for regular cardio for a period of 45 minutes and 60 minutes with proper diet to achieve that. After that I would suggest you to balance your input and output properly for long term.
Take care!