http://nuclearcdboxafziza4mgohcwhzfjiyg6zeslnry33pepsgtur2wyeyd.onion/social/thread/200.html
You'll see cheesy management mnemonics like 'SMART goals', but they do have a point:
Have a specific goal, not just 'be stonger' but, say, improve a specific exercise or body part or dietary need.
Have a measurable goal, which you can quantify. I can tell how close I am to a certain 1RM. I can't tell how close I am to 'being strong enough to dunk a riot cop'.
Make sure it's realistic, failing goals repeatedly is bad for morale.