Very simple, I always preferred natural ways in this regard. Swimming is the best exercise that burns lots of calories. No doubt a relaxing form of exercise means weight lost by swimming is fun too! Sure this will be helpful for you lose weight.
You asked her if she wanted to grab coffee. Then you asked if the time worked. Then you asked if the place was okay. Then you asked if she'd prefer tea.
Four questions. Four chances for her to say no. Four signals that you're terrified of making a decision.
Plan it. Pick the place. Pick the time. Tell her where to meet you. She'll either show up or she won't.
Either way, you look like a man instead of a scared little boy.