Joining this quite late, but my holiday is in 13 weeks today, and I'm currently 203lbs. Ideally I'd like to get down to as close to 170lbs before then as I can. So to achieve that I'm basically cycling on the exercise bike for half an hour a day (at quite a vigorous pace), along with sit ups/push ups. I'm also keeping my calories below 1500 a day. How achievable is my goal?