Muscles have a very good blood supply which results in noticeable gains in strength in a relatively short time. The connective tissue does not respond with the rapidity, partly due to a lesser blood supply. Every single book about physical training discusses the necessity of gradual increases in effort. To begin training with intensity is the opposite of what is needed. Over time you will get stronger but think of exercise a lifetime endeavor. The benefits will accrue like compound interest, a little bit at a time.