perhaps try HIIT? stands for High-intensity interval training, say for example, on a treadmill, do your usual warm up, then 30 seconds brisk walk, 30 seconds sprint, repeat, try and work your way up to 75 sec brisk walk 60 sec sprinting, same on the bike, 30 seconds at aprox 80-90RPM 30 sec +120RPM (that all depends on your fitness level) you kinda wanna work it on a scale of 1-10 1 being minimal, 5 being brisk walk, 7 being walking/jogging and able to hold a conversation, 10 being as hard as you can go, so you'd wanna go 30 secs at level 7, 30 secs at level 9/10, 30 secs at 7, 30 secs at 9/10, for around 10-15 mins, try doing this for 10 mins on the bike, 10 mins on the treadmill, 10 mins on the elliptic and 10 mins on the rower. dont forget to warm up and cool down properly and stretch!
Thats my advice