I second big jim. The body needs rest to rebuild muscles. You should shoot the heavy bow every other day. Also, You should try working out 3 times per week if you can. Pull ups are good. Seated rows are better, so are face pulls, back flys, etc. If you can find a thick rubber weight training band, and practice pulling that just like a bow, that'll help. When I was a college athlete and lifting every day, pulling a 70lb was cake. Now I have to work out and do the excercises I just shared with you to keep in shooting shape.
P.S. If you're sore from lifting or shooting, Dont be too hard on yourself if you're not very accurate. Use the sore days to rest, not shoot and try to improve your accuracy.