Shortness of breath

Hi Ladies. I am 19 weeks and 3 days pregnant. I work in a warehouse and I feel like I have to take a break every 30 minutes to catch my breath. I have recently got checked by my doctor, blood pressure and had an ultrasound done and my baby girl is healthy :) I've also mention this to my boss and she's been awesome and understanding and told me to take it easy but I'm still having this problem just wondering if anyone has dealt with this and know what can help solve it? Thanks