Fire stairs when you are on holidays (in my case) and it's raining
The 'extreme' low cost exercise of running stairs is an efficient way to reach your goal of derriere toning and improve cardio fitness.
No need for any expensive equipment or to find a local gym ...just a good pair of runners and a set of stairs and you are all good to go.
Being accessible both indoors and outside it is perfect in all kinds of weather. During great weather, treat yourself to running stairs at a local beach or if the weather is foul run the stairs inside a suitable building.
We have no stairs at home ...