I'll follow jmezs lead....find a program, stick with it and give yourself time to achieve the results you want. As he noted there are many ways to achieve your mt fitness the key is to be consistent with whatever method you choose. I live on a treadmill and stairmaster for the simple reason it is low impact and can fit it into my schedule easily. As to pack training mix it up and don't over due pack training especially as you get older...staying injury free is key as set backs suk!