West Cook YMCA




FairweatherLiz Fairweather
Personal Trainer/Group Fitness Instructor

I have been an aquatics and fitness instructor at the West Cook YMCA since 2018, but a fitness and sports enthusiast my entire life, from gymnastics and diving to sailing and skiing. My primary focus was gymnastics, where I earned a record ten state titles in Wisconsin and then was twice named an All-American at the U.S. Air Force Academy. I have recently transitioned my interests to distance running and triathlons, and currently serve on the board of Best Foot Forward (BFF), an Oak Park women’s running group. When I first moved to Oak Park two years ago with my family, I was seeking both a new calling and community; I was fortunate to find both at the West Cook YMCA with its holistic focus on one’s mind, body, and spirit. I have enjoyed sharing my passion for health and wellness with fellow Y members, and I look forward to bringing my experience and enthusiasm to the Y community.

Certifications: NASM Certified Personal Trainer, AEA Aquatic Fitness Professional, YMCA’s Diabetes Prevention Program Lifestyle Coach, Healthy Weight and Your Child Leader, Weight Loss Program Facilitator, LIVESTRONG at the YMCA Instructor

Frank kumkoski

I've been personal training and teaching group exercise classes since 2012. I began my career training older adults at an assisted living facility. I have strong interests in strength/power, balance, and cognition in this population. I have also worked in outpatient cardiac rehab, children's bariatrics, and a multitude of other diverse clientele. Generally, I believe everyone needs a baseline of strength and mobility to have a high quality of life. 

I love playing sports including recent interests in racquetball/handball, basketball, and volleyball. My favorite fitness equipment is the kettlebell. 

I came to the West Cook YMCA to positively impact the lives of my community through educating and promoting healthy lifestyle changes. 

Certifications: M.S. Ed. Exercise Physiology/Fitness Leadership, ACSM Certified Personal Trainer 

Personal Trainer/Group Fitness Instructor

I have been a certified personal trainer since 2007. The sense of family and community drew me to the YMCA organization. I get the most enjoyment being able to teach clients/members about physical fitness and how to customize their workouts according to their needs.

Certifications: ACE Personal Trainer, ACE Group Fitness Instructor, RKC (Russian Kettlebell Certified), Battle ropes Certified (John Brookfield), Functional Movement Screen Certified, Selective Functional Movement Assessment, Y-Balance Test Certified, HKC (Hard style Kettlebell Certified), Diabetes Prevention Program Lifestyle Coach, LIVESTRONG at the YMCA Certified Instructor, Enhance Fitness Instructor

Marissa stevens
personal trainer/yoga & fitness instructor

I trained as a yoga teacher in 2019 and quickly followed that with a certification in group fitness instruction. My journey toward health and wellness began when I was young. With a background in tennis and competitive swimming, I always knew movement was an important aspect of a well-balanced lifestyle. In 2015, I began to explore how embracing diverse elements of fitness could unlock some amazing experiences and challenged myself to learn new skills such as skiiing, mountain biking, and scuba diving. 


I believe that movement is for everyone. I am thrilled to be a part of the West Cook YMCA community and wish to support our members in enjoying life on their own terms through their own health and fitness paths.


Certifications: Certified 200 Hour Vinyasa Yoga Teacher, Certified Yin Yoga Teacher, Certified ACSM Personal Trainer, Certified AFAA Group Fitness Instructor

BennettAlex Bennett
Personal Trainer

I've been a trainer at the Y since 2015, though I'm also a former lifeguard, swim instructor, and skating instructor. I came to the Y for the sense of community here: that's why I knew I wanted to work here, too---to give back to that community. I love coaching and working with clients to achieve their goals because it's so rewarding to see them making progress, and because we have fun together doing it!

I'm currently working toward my Corrective Exercise Specialist certification (NASM) and my Precision Nutrition Level 1 certification. I'm also a triathlete and 2-time Ironman finisher, with #3 planned for the future.

Certifications: ACSM Certified Personal Trainer, Livestrong Instructor


PieartNicki Pieart

I have been a certified athletic trainer for 11 years and teaching classes at the YMCA for 1.5 years. I moved to the area 9 years ago. I was looking for a gym where the focus was on community. The Y fit the bill perfectly. I enjoy all of the people at the Y, from the front desk staff to the class members to the residents. I have enjoyed having the Y as a part of my daily routine. I started at the Y as a member and quickly felt at home. I was challenged by the classes and made many fitness friends who were pushing me to reach new fitness goals. As I got more ingrained in the WCY, I decided I wanted to contribute to others success! So I started teaching group ex classes and have loved taking my class participants on their fitness journeys.

Certifications: MSEd--Exercise Physiology, Certified and Licensed Athletic Trainer 


ValdiviaKathy Valdivia
Fitness instructor

I’m very happy to be part of the YMCA family and to be able to offer my knowledge and experiences as a Zumba Instructor. I have just joined this great family, but I am sure it will be a great start to plans and programs for the service of the community

I’m Peruvian and been a Folkloric Dance teacher for 30 years, I have a ton of experience in the dance stages because I belonged to a dance group for many years back in Peru and here in the United States.

I decided to train as a Zumba instructor 2 years ago with the intention of approaching people who like to dance and enjoy music. My purpose is to guide them towards a basic development of easy steps and movements for them to enjoy a fun and relaxing class. My experience as a dancer has led me to understand that it is not necessary to be a professional or expert in difficult steps to live and feel the music. It’s the inner feeling that comes out to express itself in a way that brings life from the music and makes one happy.
Certifications: Professor of Art in Folklore Dance, Zumba ZIN MEMBER Instructor




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