from the code below:
    for epoch in range(max_epochs):
            .
            .
       for i,sample in enumerate(train_loader):
            .
            .
            mr = sample[0].float().to(device)   #torch.Size([batch_size, 1, 32, 32, 32])
            print(mr.mean())
            ct = sample[1].float().to(device)
            print(ct.mean())

and the mean of the train and validation samples are.
train directory has 8000 samples
valid directory has 1000 samples
training ...
train input: 46.612483978271484
train target: 120.2796859741211
train output: 0.11282896995544434

validation input: 46.15531921386719
validation target: -71.48211669921875
validation output: -0.17590099573135376