Every city has a staircase, and every staircase is a free strength session. Climbing forces you to lift your knees, drive your arms and push hard off each foot, which is exactly what fast running asks for.
Find a flight that takes fifteen to twenty seconds to run up. After a proper warm-up, run to the top at a strong, controlled effort and walk back down. That is one repeat.
Start with six repeats and add one each week until you reach twelve. Keep your eyes up, land on the ball of your foot and take every step rather than skipping any, at least for the first month.
The walk down is your recovery, so do not rush it. Going down fast is where most slips and sore knees come from.
Do this once a week in place of a short run. Within a month, hills feel flatter and your normal pace feels easier, because your legs have learned to produce more force with every stride.