First, cool down. You're fessing over what's really a non-issue. Most death threats are unfounded. Let him have some time to cool down, and then maybe you can work it out.
Second, report it to the police. Death threats are often serious crimes, and the police will deal with it. You're better off just ignoring things after that.
Third, don't just ignore the posts about getting more exercise. If you can, do. A more well-toned body has many benefits: higher metabolism, lower heart rates, and some studies even show that muscle mass correlates with happiness. Don't body-build to fight people, but do body-build to improve your health.
And fourth, get a girlfriend. Too many people nowadays wait too long before they do so. Humans are happier when paired with other humans; this has been the case since we evolved. Careers shouldn't take precedence over family. Having a girlfriend also has the benefit of dispelling suspicion in other men.
Training + girlfriend.
+1000 !!!
I would also like to add that, you don't have to 'bodybuild', but just focus on compound lifts (deadlift, squats, bench press, rows, chins, dips), eat well, and do some cardio - walks, jogging etc. It's a great lifestyle! You will feel better about yourself, you will become a mountain of a man!
