Stress Incontinence. Kegel exercises are an excellent way to strengthen the pelvic floor. However, you should have an evaluation to make a diagnosis. Based on the finding, your doctor can recommend a treatment.
Exercises & destrain. Some of the approaches depend on what you mean by "weak bladder." it sopunds like some incontinence, or inability to control your urination. Pelvic floor exercises (link: http://www.Nafc.Org/stress-incontinence/index.Php?Page=pelvic-muscle-exercises&gclid=cmfk153n6k0cfyfb7aodez-s7a) can help, but you have do do many! also, being sure not to strain with exercise or lifting is important.
Kegel exercises. Pelvic floor exercises. Start by tightening and relaxing the pelvic floor muscles twice a day. You should do approxatley ten repetitions at first and then work up to doing ten three to four times a day. This will help gain control.