I am not any sort of trainer, but my suggestion would be a minimum of continuous aerobic exercise (walking) for 30 minutes at least 3-4 times a week. I know you stated you dont like the gym, but you may also want to be mixing your regimen with strength exercises (weights) about 2 times per week. It does not have to be strenuous, if you re not looking for building mass, but is good for keeping your major muscles tuned.
If possible, see a doctor for the best recommendations based on your current health, age and any conditions you may have, since your doctor will know/find out these things. The ultimate goal of finding these things out is to find your best current target heartrate and maintaining it for an amount of time. 220 subtracted by your current age is your max heartrate, and will give you the most out of exercising; just be sure not to overexert yourself.