I second the notion of a sling, or a soft harness carrier like the ones made by Snugli or Infantino. That way the baby gets held like she needs & you can still get some exercise in by walking. Right after I had Linda, I bought one of Jorge Cruise's
8 Minutes in the Morning books and used that for easy & relatively quick exercise during her naptimes. Another good book is
Yoga Mama, Buddha Baby, which is a book full of yoga to do with your baby. For some of the asanas you hold her, for some of them she's just near you. If you time some yoga to her quiet alert phases, she might just let you sit her down and amuse her.
Congratulations, by the way!