I've been riding her daily, about 30 minutes a day at mostly a walk. Very occasionally I will ask her to trot a little, but she can't do it for long and it almost sounds like she's getting winded at a trot. Now I know it's not fair to compare human and equine fitness levels, but I remember how I was when I first started running and was overweight, so I'm hoping that she's just out of shape winded and trotting with a rider is cardio intensive. She doesn't sound "wheezy" and isn't coughing and is rather willing to try. The previous owner was very honest and has kept in touch and has never had any health issues with her. I have not pushed her under saddle, just asked her to try and do the best she can since we're working on a slow reconditioning plan.
So I guess what I'm wondering is if anyone else has experienced this with an BBM (Big Beautiful Mare!) or if I should have other concerns.