Sports conditioning and fitness organizations recommend that you strength-train three to four times a week and change your strength-training routine every six weeks or so. They wouldn't recommend switching routines completely each time you exercise. Instead, pick one of these programs and do it for a few weeks. It will take a couple of sessions for you to figure out the right amount of weight to lift and how many reps you should do of each move. The way to stay strong isn't to just keep lifting heavier and heavier weights. Put some thought and planning into your program.