When to decide if you need to lose weight?

I went to my doctor this month and my weight had increased quite a bit in the last two months. I had been careless in my diet, eating at the wrong time, eating extra portions and also indulging in those not very healthy foods. Overtime it was bound to show. So my doctor told me to watch out and gave me some friendly tips. I was not alarmed; I mean what are a few pounds here and there. I was okay; my BMI was more than 25 so maybe I needed to change. Then there was the effort I had to make while walking up the steps. The jeans did not fit and also there is that cute fat that had settled around my waist. So maybe it is time for me to lose weight.