A VFR PA32 PLT ENCOUNTERED IMC DSNDING INTO ZZZ1 AND SO DIVERTED RECEIVING SVFR VECTORS TO ZZZ.

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ON A RETURN XCOUNTRY FLT; I FOUND MYSELF INADVERTENTLY FLYING INTO VERY MARGINAL VFR CONDITIONS 40 MI N OF ZZZ1. I DSNDED TO 1000 FT AGL OVER THE LAKE AND FLAT TERRAIN TO MAINTAIN 8 MI VISIBILITY AND GND CONTACT. I REALIZED THAT I WAS FLYING INTO RAIN SHOWERS THAT REDUCED VISIBILITY TO 1 OR 2 MI. I STILL HAD GOOD GND CONTACT. I ELECTED TO DISCONTINUE MY APCH TO ZZZ1 WHICH WAS STILL RPTING VFR BUT MIGHT HAVE REQUIRED FLYING THROUGH MORE RAIN SHOWERS/POOR VISIBILITY; AND DIVERTED TO ZZZ. ZZZ ARPT WAS RPTING 6 MI VISIBILITY AND 900 FT CEILINGS AND IFR. THE TWR WAITED FOR ME TO REQUEST SVFR AND THEN VECTORED ME IN. TO HAVE AVOIDED THIS; I SHOULD HAVE NOT PASSED BEYOND MY PERSONAL MINIMUMS (WHICH ARE ABOVE VFR MINIMUMS); MADE SURE I HAD SUFFICIENT FUEL TO A PRE-SELECTED EASY VFR ALTERNATE; NOT GET CAUGHT FLYING BELOW A LOW CEILING WHICH IS LOWER THAN SURROUNDING TERRAIN; ESSENTIALLY BLOCKING MY RTE TO AN ALTERNATE AIRFIELD. I WAS MENTALLY PREPARED AND HAD REVIEWED SEVERAL ALTERNATES BUT WAS STILL FIXATED ON MY INTENDED DEST. PROLONGED VFR FLT INTO DETERIORATING CONDITIONS -- BAD IDEA.