Filling my "free time" in early sobriety (and many years thereafter) was a no-brainer for me...AA meetings...morning, noon, and night! There's a saying in AA, "Once you take the alcohol away from the alcoholic, you'd better have something to replace it." You'd be surprised at how many fun activities are planned by AA/NA groups.
Aside from AA/NA, there are a few things you can do on your own: movies, treat yourself to dinner, museums, sporting events, plan some travel with the money you'll save not drinking, skiing, dance lessons, adult classes, singles groups. Get creative in your activities...it may take some planning, but it will be worth the challenge. Let us know what you come up with.