Illig has raced marathons, ultra-marathons and triathlons, has played three seasons of team tennis in Germany, and for the past 20 years has been an intercollegiate squash coach - - at Middlebury (2007-2012), at Bates College (1996-2007), and at Colby College (1991-1996). He is the author of three books (Pacific Dream, Man in the Middle, and Trail Ways, Path Wise), * and he has through-hiked the Appalachian Trail, the Pacific Crest Trail and the Continental Divide Trail, logging over 8,000 miles.

The former President of the women’s College Squash Association, Illig's teams have finished ranked in the top 10 nationally eight times. He has coached three All-Americans, two CSA Ann Wetzel award winners, one CSA Skillman Award winner and his teams have twice won the national team sportsmanship award. Illig was the recipient of the CSA Clarence Chaffee Award in 2002, and was the U.S. Olympic Squash Developmental Coach of the Year in 2000.

Illig’s 08-09 Middlebury women’s team finished ranked #13 nationally, posting a 19-8 record, earning him the women’s NESCAC Coach of the Year honors. The team followed that up with a school-record 20 wins in '09-'10, finishing 14th nationally. 

His men’s team won the 08-09 national Team Sportsmanship Award and posted a 15-10 record. In '09-'10, the men set a school record with a 20-7 mark, finishing 17th nationally. The team has finished 14th nationally in each of the last two seasons.

Illig has been active in the development of junior players, having led summer squash training tours to Spain in 2008 and 2009, and to New Zealand in 2009.

A 1986 graduate of the University of Rochester, with a degree in English Literature, Illig played #1 singles and doubles on the Yellowjacket tennis team, competing in the NCAA tournament. The two colleges for which he played squash, Trinity College and the University of Rochester (Illig transferred from Trinity after one year), are currently #1 and #3, respectively, in the intercollegiate squash rankings.