Nervous about spaying our giant breed dog tomorrow?

I've had dogs fixed before and have never been this nervous before. Our 6 month old English mastiff goes in tomorrow morning for her spay surgery. I feel like we've done good by waiting till she's over 6 months old (for bone growth), and are catching it before her first heat (to reduce cancer risk) and I know she'll do fine in surgery but it still makes me so nervous. I think I'm mostly worried about her being in pain afterward, even though she'll be on pain meds and sedatives. She's rather energetic and the thought of confining her is heartbreaking. How did the rest of you deal with the confinement afterward?