Okay, a few more words. You want to do weight-bearing activities that focus on your glutes and hamstrings. Squats and lunges are great. If you're comfortable going into a weight room, deadlifts are another great exercise for this (be sure you're doing them properly, get someone knowledgeable to spot you the first few times). Squats with a barbell are also fantastic.
One thing that gave me buns of steel, even when I wasn't regularly lifting weights, was biking. Take those hills and push it.
Exercise is really the only thing you can do for a tighter butt (unless you want to lose fat off of it too, in which case you should focus on your diet). But it works, and in most cases those muscles are actually one of the easier groups to train. [ pollux's advice column | Ask pollux A Question ]
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