I've been driving a turbocharged and/or modified turbocharged car as a DD since 2002 starting with the 1st WRX, the 05 wagon, now spec b.
You don't need to go to a gym. I've never been into that. Maintaining a reasonable nutritional intake and getting a variety of exercise you can do without a lot of fancy equipment works for me. Plus a hobby or two, e.g., mountain biking (my preference) can keep you "in shape" and entertained. Read the labels, do the simple math, leave room for foods you love, even if they're allegedluh "unhealthy." Balance and moderation in all things ---- EXCEPT VEHICULAR PERFORMANCE/IMPROVEMENT !!!
Oh, for both nutrition and cars - AVOID RICE !!!!!