Improve your running form by running faster for shorter distance runs. This will train you how to run in proper form and it will give you a great leg workout too. By improving your form, you can then prevent any kind of movements or jerking that could cause serious injuries.
Never lift weights for more than an hour. If you continue lifting for any longer than that, your body will automatically activate a natural defense mechanism, which causes muscle-wasting and fatigue. Keep yourself on a strict time limit to prevent losing what muscle mass you have worked so hard to gain.