Hi,Im am so very new at this.My husband and I are joining a gym and I would like to follow the program given to me but Im so confused when it gives sets and reps...like it will say set 1-15 reps,set 2-15 reps,set 3-12 reps etc.Do I do those "sets" back to back? Is there a rest period in between? I know it probably sounds so stupid but I really dont understand the set thing.Any help would be appreciated!:(