Concerns and triumphs for today

I had a rather fast walk this morning.  I exercised early this morning so the weather was right for walking.  I meant to do some yardwork.  I feel like that while exercise has done me some good, exercise in general is not really helping me in losing weight.  Despite my record today, I am not losing weight and that has me worried.  I don't wish to give up exercising.  As a matter of fact, I walked 2.75 miles per hour for nearly 20 minutes.