General aviation pilot reported landing on a beach in soft mud which resulted in the aircraft turning over on its nose.

Narrative

I departed my home base of ZZZ at approximately XA00 local time for a short pleasure flight. Clear skies prevailed with visibility unlimited and winds out of the north at approximately 10 knots. I planned to fly over the lake. As I approached the north end of the lake; I saw a beach along the lake that was aligned with the wind and made the decision to land there. I circled the area at about 500' agl to make sure there were no people; vessels or structures anywhere near the area I planned to land. I set up for a half-mile final to the area; dropped my flaps and slowed to approach speed. I verified again the beach looked clear with no obstacles or people. I touched down on my main gear as slow as practical and immediately decelerated in soft mud. The aircraft slowly went over on its nose; but not all the way over - the tail did not strike. In the cockpit I unbuckled and lowered myself against the windshield and roof. I turned off the mags and master switch. I waited for authorities to arrive. I had no injuries and there was no damage to any property.In hindsight; it was a completely stupid decision on my part to land there. At my age; I should know better than to do something like this. There were no aircraft anomalies and no reason for me to land there.It took a brief moment of 'aviation fun' to re-learn an important lesson - that I'm never too old to learn. I deeply regret this lapse in judgement.