I completed Kayla Itsines' viral 12-week workout - and I'm thrilled with the results

I am used to working out.

I have run four half-marathons, completed the Physique 57 workout program and Ruth Bader Ginsburg's workout, and exercise regularly. I also finished one round of the Bikini Body Guide last year.

Even though I workout often, I was prepared to be sore because the exercises are tough and you complete them as many times as you can during the two circuits that you repeat at least twice.

I was motivated by the community of BBG fans who encourage each other online and offline.

The Bikini Body Guide hashtag on Instagram has over seven million posts. BBG fans share their BBG progress and BBG transformations and frequently leave encouraging comments and advice. People even plan local meetups to do the BBG workouts together.

Each high-intensity plyometric training workout targets a different muscle group: abs, arms, and legs. Every workout incorporates two series of four exercises that are completed in seven-minute circuits, twice. You do each of the four exercises as many times as you can in the seven minutes for each circuit.

I usually did each exercise (for example 15 pushups, 15 burpees, 60 bicycle crunches, 30 weighted step-ups) twice per circuit. You get a one-minute break between circuits and a guided stretching session when you're done for the day.

I find the abs day to be the most difficult, in part because I have scoliosis and can't do all of the crunches correctly. I make modifications, like doing regular crunches instead of full-body crunches. Listen to your body and don't be afraid to modify the exercises. If you download the app, you can also check the alternative exercise to see if it works better for your body.

In addition to the three plyometric training workouts, you complete three low-intensity steady state cardio workouts (LISS) for 30 to 45 minutes, one high-Intensity interval training session (HIIT), one 10-minute guided stretching session, and one much-deserved rest day.

Itsines suggests power walking for LISS, but she says that you can also do yoga, swim, go for a slow jog, or take a leisurely bike ride. The key for LISS is to keep your heart rate low and to go at a steady state. In the one high-intensity interval training (HIIT) workout a week, you alternate between sprinting and walking and repeat for 10-15 minutes. I usually speed walk 20 blocks for LISS and run in Central Park or on the treadmill for HIIT.

The updated SWEAT app released last year has three additional 12-week workout programs so you can add variety to your workout routine.

The new workouts feature a variety of trainers and programs like yoga instructor Sjana Elise Earp's "Body and Mind" (a Vinyasa-style yoga and recovery workout), Itsines' BBG Stronger (a BBG-style workout that incorporates gym equipment), and certified trainer Kelsey Wells's Sweat PWR (a weight training and resistance workout), and Post-Pregnancy (a post-natal program that focuses on core strength).

I haven't done the full 12-week BBG Stronger program yet, but I've tried a few sessions and like that it teaches you how to use fitness equipment correctly. I plan on trying the yoga classes on LISS days.

I'm done with BBG Round 1. Now I'm starting BBG Round 2, which is twelve weeks of even more challenging workouts. I feel stronger and more toned from completing BBG. The workouts get progressively more difficult and you also incorporate HIIT for weeks nine to 12. I always feel proud of myself by the end of each 28-minute workout and HIIT session.

I feel healthier and empowered from doing BBG. The program helps me stay accountable because I want to check off all of the required workouts each week. (I use the app and the quote at the start of the workout, and the confetti and trophy it shows at the end of the workout is surprisingly motivational.)

I feel more toned and can definitely do more pushups, burpees, and commandos than I could at the start of BBG. But my biggest qualm about BBG is that all of the transformation pictures can be disappointing if you don't finish the 12-weeks with abs and a drastic transformation.

Although I feel stronger and more toned, my progress photos from the start of BBG to the finish aren't substantially different. But I try to remind myself that everyone is different and that the major transformation might not happen for me in the first 12-weeks. Also, I feel less stressed and happier when I workout regularly which is beneficial on it's own.

I recommend Bikini Body Guide. The 28-minute workouts and short HIIT sessions are quick and convenient and you can do them from home. The workout program can fit into your busy lifestyle better than an hour-long class, and it helped me stay accountable. Everyone's fitness level and experience is different, but it has been beneficial for me.

After finishing all 12 weeks of BBG, I can confidently say that it works. You'll be sweaty, and you'll savor the minute-long break between sets, but at least your hard work will pay off.