You can kill many birds with one stone (figuratively speaking) if your stone is swimming. It activates every muscle in your body. It’s perfect if you don’t like being sweaty because the water keeps you cool even though your heart rate is rising. You can swim for 20 minutes and enjoy the same health benefits as if you were running for 40-50 minutes. It builds endurance, muscle strength and improves cardiovascular fitness. Swimming is also cheap – all you need is a swimming suit. It can also be a lot of fun if you take your kids you friends with you.