Today do some cardio that challenges you.
If you usually walk – do sets of sprints.
If you usually jog on cross trainer – increase resistance and go for intervals.
Rowing – sprints again!

Doesn’t have to be gym based, in fact, training outside hits another great point in addition to fat burn, which we need for our abs purposes: your willpower – YOU decide when to exercise, things like “when I go gym” or “when the weather is better” might be not this month, developing the habit of training independently of external conditions makes working out much less of a chore.

Here are some intervals ideas for 15min cardio boosters

Always warm up well. Very important 😁

Start with 2mins steady, then do your intervals, then 2mins steady cool down

Outdoors:
Walk approx 100mts (note trees or houses), then jog approx 100mts – repeat 6 times
Jog approx 100mts then sprint approx 100mts – repeat 6 times
Hill sprints – 6 times
Stair runs – 6 times

Gym
Treadmill – 1min work / 1min recover x 5
Cycling – 1min work / 1min recover x 5
Cross trainer – 30sec work / 30sec recover x 6
Rowing – 20sec work / 20sec recover x 8

Whatever you choose to do, see that you are using the right muscles and engaging your core (we all know what difference it makes rowing when abs are working!), and obviously be safe and choose exercises and scale intensity according to your health, no treadmill if your knees are hurting…