Cultivate interests that appeal to you. Those interests will probably appeal to people you will want to date as well.
Of course, it's not going to work if you end up having no real interest in these things, but if you do, then you might take these interests off of the back burner.
Another common fallacy is that you can weigh 300 pounds and yet attract a 110 lb waif. It's been known to happen, but the odds are stacked against you.
For guys, being skinny isn't considered that attractive though. Better than being fat, but not as good as being buff.
I am not particularly buff, and I've had about a dozen girlfriends, and have "dated" another ten or so. Now if only I could meet the right one....