I've been doing it for years, and some days, one shoe won't go (sometimes the cleats just need to be adjusted). The harder I try, the less my shoes want to clip in. Stop. Take a cleansing breath. Gentle pressure while gently moving your foot around to find the right spot (pushing harder doesn't usually help). A a few "Ohms" don't hurt
It's kind of an art, I guess.
"Well-behaved women seldom make history." --Laurel Thatcher Ulrich
'09 Trek WSD 2.1 with a Brooks B-68 saddle
'11 Trek WSD Madone 5.2 with Brooks B-17