Putting your phone inside pocket: Your testicles need to maintain a temperature about two degrees Celsius cooler than body temperature which is why your testicles are located outside the body in the scrotum. Keeping mobile phone in your pocket, pressed against your skin, increases skin temperature by more than 2 degrees Celsius which may be enough to reduce sperm motility or kill sperm cells.
Phones also emit radiations which have been proven to affect sperm morphology(shape).
Hot Baths : Having a prolonged hot bath can affect sperm production
Excess Alcohol : Excess alcohol quickens the conversion of testosterone (primary male sex hormone) to estradiol ( primary female sex hormone) and that is not good for sperm production .
Smoking: Smoking reduces sperm count and motility
Stress : Allowing your self to be stressed up can also affect sperm production. Stress affects production of certain hormones which in turn affect sperm production.