Power racks are perfect for training by yourself safely. I have done it for over 30 years! Power racks have spotter bars which can be adjusted to your shape, size, and exercise that you are performing. For example, on squats, set the spotters the position below your bottom out points. This will save you from being crushed by the bar if you can not complete the rep. Initially it will take a couple of workouts until you know the perfect positioning of your spotters. If your power rack uprights are not numbered just use a marker or some tape. After a couple of sessions you will be able to move the spotters around effortlessly.