Want to know about Jessica Biel's butt workout? Or how Jennifer Garner slimmed down post pregnancy? Discover more about their celebrity workout routines.

Valerie Waters spills the secret fitness tips of her A-list clientele. Follow her balanced healthy diet and exercise plan and you too can have a star-quality body.

Q: What are your diet and fitness tips for getting bikini ready in a short period of time?

A: Commit. Plan Ahead. Eat Clean. Eat Breakfast.

Make your workout routines count. You make them count by strength training your whole body 3 days a week. Focus on the big muscles: legs, chest, back, arms. The other 3 days you do interval training. That's how you're going to burn the most fat. You can run or do intervals on the bike or the elliptical: 2 minutes hard and then ease up for 2 minutes. On the seventh day, you can rest or do an active rest like yoga, Pilates or hiking.

Q: You're also a food coach to your clients. What's your balanced healthy diet philosophy?

A: I abide by the 90/10 rule. That means 90 percent of the time you're going to fill up on healthy foods like lean proteins, low-fat diary, fruits and vegetables, such as Florida grapefruit, spinach and broccoli. A diet with 90 percent of healthy foods leaves room for treats 10 percent of the time. I believe we should have something that satisfies us each day. It may be a piece of dark chocolate or slice of pizza. That will sustain us in the long term. I believe diet is 70 to 80 percent of it, but you need to exercise because exercise changes your shape.

Q: You've worked with Jessica Biel, who is known for her shapely butt. Can you recommend some booty-firming butt workout moves?

A: The Val Slide is the secret weapon for a lot of celebrities because it will change your butt faster than anything you've seen. It's like using a slide board except that's it's smaller. So you can slide into a reverse lunge and because it keeps continuous tension of the muscles, it creates more shape faster. It feels like it's fun and easy, but it kicks your butt. You can do so much of your butt workout with no equipment: squats, lunges, step-ups. My clients don't want big quads, so I don't do a lot of heavy weights or leg presses.

Celebrity trainer Valerie Waters shares more fitness tips for Shape readers.

Q: How can people create workout routines on a budget?

A: You certainly don't have to be a member of the gym. There's so much that you can do in your living room. Start with your body weight: squats, push-ups, planks, step-ups. These are key because they're effective. You don't need to invest a lot. You really just need a couple key things for these workout routines: a stretchy band with handles, dumbbells and ideally a stability ball because you can use that as a bench and do chest presses or crunches on there. It's maybe a $60 investment in yourself and your fitness.

Q: You helped Jennifer Garner get her pre-baby body back. What fitness tips and recommendations do you have for new moms who want to slim down?

A: Moms tend to get a bit overwhelmed and sleep deprived, so when that happens you want sugar because you're trying to bring your energy back up. When people don't eat right it's usually because they don't have a good strategy in place or they didn't plan ahead. When you're cleaning up from dinner, make your lunch and put some snacks in baggies, so in the morning you have healthy foods ready to go.

New moms want to spend all their time with their babies. If they can spend 30 minutes in their exercise program taking care of themselves, it not only helps with their strength, but their stress as well. If you have that half an hour to let things go, I believe you wind up being a better parent. You feel better after going through workout routines, so make that effort to put yourself first.

Q: What are common misconceptions about how celebs get in shape?

A: You can't just drink hot water and lemon for two weeks and be skinny. You can't live like that. Jennifer Garner does not walk around like Elektra all the time -- that was our ultimate body, but that's so restrictive of calories. She may stay within five pounds of that and feel great and look sexy and hot. I want to teach people how to eat healthy foods and exercise so that they can do it for the rest of their lives.