It's ok to take your car if you feel burned out. I started to let myself have 1-2 "car" days a week for about a month, and it was definitely a relief in terms of stress, scheduling, and fatigue. The best part is that you'll almost definitely get accustomed to the bike ride faster if you don't overdo it, and you'll go bike-free faster as a result. I pat myself on my back if I go car free for at least 2/5 weekdays, and happily, I've been going 4/5-5/5 car free consistently for the past 4 weeks.