Making exercises more effective isn't about loading more weight. It's about making the easy exercises harder. And many times you can do that with your own body weight.
This philosophy is particularly important for rehab/prehab. It keeps the risk for injuries or adverse reactions low.
If you can't feel something, loading more weight isn't always the best option (sometimes it is). The better option is to alter the movement.
For example, in the single leg deadlift, reaching with your opposite elbow will help activate your glute. If it doesn't, you may need a different cue. But don't always reach for the weight first.