It’s a must to take a walk down to the barrage in Cardiff bay but if you can’t walk then why not a take a bike or a quad?(a two seater, 4 wheeled bike that tends to take up the entire path its cycling down) You can hire them from Pedal Power in the bay from £4(£3 in you’re a member) and cycle to your hearts content. If you have the energy and inclination you can cycle them all the way to Merthyr via the Taff trail.