Congratulations. Cycling to work is awesome. And 20 miles is some workout. I only have 5 miles but occasionally when the weather is great I make detours to get some extra miles. I have been doing it for about 3 years now. Initially twice a week. Now daily. Meanwhile I only take the car if I really have to. Once I week I bring a set cloths for the week in a little trailer. On the other days I just carry a laptop in a pannier.
I can leave my stuff in a locker at our gym. When I come in I spend another 30 min or so in the gym on strength exercises recommended by my physical therapist. I am already sweaty so no need to change for the gym. Then shower and off to my desk.
I just love being outside in the fresh air. No matter if rain or shine. And the exercise feels good.