Congratulations on your new "soon-to-be" status! My grandson is the single most wonderful addition to my life in a long, long time – it's been 7 fabulous years of grannyhood.
At 66, I'm gradually accepting the fact that I don't feel or look young anymore, at least physically. I've never given much thought to fashion beyond looking presentable, thank heavens, because now comfort is front and center. This is what works for me. I do stay active, as mentally and physically involved as each day will accommodate. And each day is different, for me.
The one real concession I've made is using henna on my hair, which was naturally carrot-red, not a color I've loved, but it feels like "me." About 10 years ago I began developing multi-colored patches randomly around my head, stark white on one side, a horrible pinky-beige on the top, pale red on the other side, and auburn at the nape. YUCK! So now I henna it all a dark auburn.
I'm with you – enjoy the life you've got. Nobody else can tell you what parts of you to value, and what parts to change. If your life now includes noticeable aging, enjoy fighting it if that's what blows your skirt up, or enjoy settling if that's where your greatest peace lies. I think most people seek a balance between the two. But change is inevitable, and fighting it without grace or gratitude is usually a mistake.
Added: I agree with other responders that it's important to exercise. I disagree that this "will" avoid "the bad kind of old." I would love to be able to dance, do yoga, run. But for the past decade plus, I've been slowed down a lot by a rheumatic condition that makes movement painful for most of my body. Pushing too hard can significantly cripple me for days or months. So even good things like exercise need to be applied with common sense.